Venturi Orifice Steam Traps

http://www.ornl.gov/~webworks/cppr/y2001/rpt/109273.pdf

Thanks for that. I have read it before.

This speaks more of orifice plates rather than venturi orifice traps or orifice tunnel traps which are vastly different.

I was kind of hoping to speak to someone with some practicle experience with these traps.

I started working with orifices in the 1970's in the US Navy. My company has been in business working with steam and orifices for about 15 years.

www.AnchorElite.com Dean@AnchorElite.com

Thanks.

Dean

Here is another little study that might interest you. http://www.gemtrap.com/pdf/Queens%20University%20report.pdf

I do a fair amount of steam work here in Las Vegas. I have had a bit of experience with orifice traps but nothing significant. I am however going to take another look at their use.

Re: Venturi Orifice Steam Traps. What does the principle operating features of Venturi Orifice steam traps consist of, and how does it operate? When condensate enters the venturi section, it creates a temporary pressure drop causing the condensate to flash to steam, and since steam volume is much greater then the volume of liquid condensate, it causes an increase in pressure, shutting off the condensate flow. These two reactions happens continuously and with great speed making it hard to realize that the flow of condensate is actually a pulsating flow and not a continuous flow. When the Venturi Orifice steam traps are properly sized, they work well; if not they perform poorly; If condensate is not present, or only present in small amounts, live steam passes to the condensate return system, even with temperature and pressure control devices in service. Most Venturi Orifice Steam traps work best when properly designed for orifice size and flow specifications. Re: Venturi Orifice Steam Traps. The most positive result of a steam trap was" when the first steam trap was introduced around 1912,"It saved hundreds of thousands of lives by reducing steam explosions in industrial factories and apartment buildings using live steam for heat ", the negative item about a steam trap is it was never designed for efficiency. Re: Replacing Steam Traps. A new patented technology is available, designed to replace the 95 year old steam trap design, where steam and condensate were trapped together. This new efficient condensate controller is designed to control steam energy, safely and efficiently. The ECC (short for electronic condensate controller) does not trap steam and condensate together, the ECC removes condensate as it forms in the controller. Designed to keep steam separate from condensate, steam hammer is reduced to almost total elimination in the condensate return piping system. When trapping steam and condensate together in the old steam trap systems, condensate was the same temperature and pressure as the operating steam system. As soon as the condensate left the trap any reduction in pressure or combining with cooler condensate would create steam hammer. The ECC is designed for the condensate to be discharged into the condensate line with no flashing off, no Steam is discharged from the ECC, only condensate. This reduces steam hammer. One operating ECC properly engineered, can replace a series of steam traps. An ECC unit was successfully installed in a corrugated box plant, replacing 27 medium sizes Armstrong Bucket Trap. Results included an increase in quality production, a reduction of off quality products produced along with reduced maintenance repair costs . This Corrugated Box plant realized a10 percentage gain in energy efficiency. Reducing energy consumption, reduces fuel costs, total amount of Green House Gases going up the Stack is also reduced as less fuel is burned in boiler. Conserving thru Efficiency DonnieH

Did you have any luck looking into venturi orifice traps? If you are interested we could assist you. www.delta-industries.com

Overall, an orifice steam trap is a compromise between either having the orifice very small (to ensure live steam does not discharge into the condensate return line and increases the likelihood of water-hammer) or too big (and passes live steam, which we all can agree is not energy efficient, AND can cause serious problems in the condensate return line and DA/Boiler Feed tank).

Over time, the orifice size increases due to erosion of the orifice and will pass live steam (how long this takes is based on your steam quality and original size of the orifice) or plug shut (if it was a very small orifice).

The VA Hospitals have banned the use of orifice traps at any of their facilities, and Oak Ridge National Laboratory was commissioned by the US Department of Energy and has found orifice type traps to be the least desirable of all the trap types (http://www1.eere.energy.gov/industry/bestpractices/pdfs/orificetraps.pdf), and these types of traps are not incentified by rebates (if you are lucky enough to be located in California).

If energy efficiency is your goal, then I would suggest the following:

1. Use the right trap for the right application.

2. Standardize your trap population for ease of maintenance & troubleshooting

3. Have an annual steam trap survey

4. Create a preventative maintenance schedule for your steam traps.

5. Insulate your steam & condensate return pipe

6. Let your heat exchangers operate in a vacuum

7. Cascade your high pressure flash steam into your low pressure applications

8. Use boiler blow down heat recovery

9. Use flash steam to pre-heat water

10. Install stack economizers on your boilers

11. Use lower pressure steam for hot water applications that need to be less than 180 deg F

With regards to the energy savings on changing out a traditional steam trap with an orifice trap, what do you attribute the energy savings to? I can't imagine an orifice trap would be more energy efficient unless the existing steam trap (either at the air vent or the seat) was failed open and passing live steam prior to being installed.

A fair comparison would be to install a functioning float & thermostatic steam trap and an orifice trap in parallel, and valve one out for a month and gather data, then switch valves and gather data for another month and compare. I would expect, if they are both functioning correctly there would be no significant difference.

The real energy savings in a heat transfer application is if you can allow the heat exchanger to operate in a vacuum, thus allowing the condensate to create flash steam in the heat exchanger (instead of downstream of the steam trap) and discharging condensate below the critical point. This can be done with an Automatic Pump Trap.

In a nutshell: The US Department of Energy does not endorse orifice type traps - and that is because they break the #1 principle of a steam traps job: CLOSE AT THE PRESENCE OF STEAM.

This picture shows the two 50mm flanged Spirax float traps that were replaced for trial purposes.

There is a steam flow meter on this application which clearly shows an 8% average saving when you compare the steam usage on the brewing kettle from when the float traps were fitted NEW and when the venturi orifice traps were fitted new.

The brewery also found that they were able to run on average three more cycles before needing to CIP as apposed to when they ran with the Spirax float traps. We are not sure why this is but it is definately an advantage to the customer.

These have been running for over 8 months now with no negative change.

On another plant that was doing steam trap checks monthly and was either fitting spare parts to two or three or replacing traps traps at each inspection we replaced all 130 traps of which before the trap conversions we tested all existing traps ultrasonically. Only two were found to be blowing steam and both were on a very low pressure 1/2" line. After the conversion (2 years ago) we have not had one issue of failed closed traps on this plant again and they have had a reduction of 12% on fuel usage for their boilers. Not only have they saved money on spare parts, new traps and boiler fuel but also on maintenance for repairing these traps.

Yes the venturi orifice traps do leak a very small amount of steam but we have found that it is negligable especially in comparison to when only one trap on a plant fails open.

Why not give me an application and I will send you a trap for you to test for yourself and then we can discuss this further.

Regarding the report from Oak Ridge National Laboratory they themselves state: "This guide focuses only on orifice plate steam traps. At the present time, insufficient information is available to include discussions about other configurations of orifice traps, such as venturi and variable orifice traps. As the needed information becomes available, similar guides for these devices will be developed."

The traps we are using are vastly superiour to orifice plate steam traps. It is like comparing a carburettor to fuel injection.

"We may be based in the tip of Africa but we still know steam."

I'm still having a difficult time understanding the venturi orifice trap efficiency over a float style trap, so help me out:

"50mm flanged Spirax float traps".

What was the installed steam load demand?

The 2" float trap is a double seated trap, and if it is oversized for the application it will blow by live steam.

Based on the 8% efficiency improvement, it seems to me that the customer has installed a trap that was grossly oversized for the application, and the efficiency improvement they achieved was from moving to a steam trap that only passes a little steam instead of the incorrectly sized and selected steam trap.

"run on average three more cycles before needing to CIP"

If they are no longer blowing an excess of live steam by due to the trap not being significantly oversized, then their heat up times would increase because the steam would have a chance to sit in the jacket and transfer its heat energy and return to condensate.

Can you confirm what the capacity is for the orifice trap installed and how that compares to the maximum instantaneous load needed for the process?

"another plant that was doing steam trap checks monthly and was either fitting spare parts to two or three or replacing traps traps".

A steam trap either fails open or fails closed.

Failed open is caused by the trap not being able to properly seat and shut-off (unless it is oversized for the service, then it is not a product problem, but a product selection problem)

Failed closed traps are caused primarily from dirt/debris in the system getting lodged in the orifice. All traps are susceptible to this problem unless they are always leaking live steam. If they were experiencing monthly issues, then:

1. Where they using adequate boiler chemical treatment? Did they change their boiler chemical treatment just prior to/or immediately after installing the orifice traps?
2. Where "Y" strainers installed upstream of the existing steam traps? If no, where they included in the installation of the orifice traps?

"the venturi orifice traps do leak a very small amount of steam"

If the trap is designed to leak steam every day all year, then over time the orifice size would get larger (similar to any steam leak - the steam continues to wire-draw and increase the diameter size of the leak over time), and would begin to leak more steam.

The job of a steam trap is to close at the presence of steam and open at the presence of condensate and NOT LEAK STEAM. A properly operating and selected steam trap will not leak steam.

"After the conversion (2 years ago) we have not had one issue of failed closed traps on this plant"

Based on your statement the traps do leak by some steam, so I would not expect the traps to be failed closed (which can create various maintenance issues in the distribution system). However, I would expect that all of the traps are passing live steam daily, and are, therefore, not energy efficient, and can be creating issues in the condensate return system and DA/boiler feed tank.

Can you clarify failed open rate out of the 130 traps installed?

What was the installed steam load demand?

We were given an average running load of 9000kg/hr by our customer which was confirmed by their flow meter.

Yes, the two Spirax traps could well have been oversized and thus giving the venturi orifice traps an advantage as these types of traps have to be fairly well sized so that they do not waste steam when too big and that they do not hold back condensate when they are too small. This is still an advantage over mechanical traps as mechanical traps are normally off the shelf items that allow this mistake to be made whereas venturi orifice traps are not off the shelf items and before an order can be processed all parameters are looked at to correctly size each trap.

I guarantee you that this is only one of many, many oversized traps on large steam applications where the mechanical trap suppliers are selling spare parts for these traps year after year due to wire drawn seats. The manufacturer is certainly not complaining about this and only seems to want to correct this when a venturi orifice trap is fitted in its place!

Can you confirm what the capacity is for the orifice trap installed and how that compares to the maximum instantaneous load needed for the process?

At 3.5 bar the venturi orifice trap will pass 9100 kg/hr

A steam trap either fails open or fails closed.

Yes, there are explainable reasons why a steam trap fails either open or closed that has very little to do with the trap itself. In a perfect world this would be fine but in many cases plants are in sub-standard condition for various reasons such as inheriting a neglected plant or poor maintenance or even badly designed or installed or sized equipment. What we have found is that the venturi orifice trap helps smooth over these problems with the least amount of hassles and still creates a very satisfactory solution.

1. Where they using adequate boiler chemical treatment? Did they change their boiler chemical treatment just prior to/or immediately after installing the orifice traps? No
2. Where "Y" strainers installed upstream of the existing steam traps? If no, where they included in the installation of the orifice traps? There were Y strainers installed in the line already that were cleaned twice yearly.

They did however have a water hammer problem due to incorrectly designed equipment. This has not been corrected as the water-table is too high in the area and they are not wanting to submerge their condensate return tanks. Due to the design of the venturi orifice traps water hammer does not affect them.

If the trap is designed to leak steam every day all year, then over time the orifice size would get larger (similar to any steam leak - the steam continues to wire-draw and increase the diameter size of the leak over time), and would begin to leak more steam.

I have only been using these traps for just over 2 years now but I have visited 3 plants where they have been running their complete plant on these traps for over 12 years without replacing them. Their condensate return tank measures 90 degrees C (194 degrees F) showing no ill effects of blowing steam.

The job of a steam trap is to close at the presence of steam and open at the presence of condensate and NOT LEAK STEAM. A properly operating and selected steam trap will not leak steam.

The job of a "traditional" steam trap is to NOT LEAK STEAM and they do their job very well. But over time for whatever reason (normally no fault of the trap itself) they do begin to leak and fail open or closed. A venturi orifice trap is not a "traditional" steam trap and WILL therefore leak a pre-calculated amount of steam which is guaranteed not to get any more over a given period (5 - 10 years depending on which manufacturer) and which WILL in the long term save a customer money through saved fuel costs, saved spare parts and saved labour as well as cutting CO2 emmissions on plants that have excessive steam trap leakage. Try not to look at it as a conventional trap. Sometimes one has to take ones blinkers off!

However, I would expect that all of the traps are passing live steam daily, and are, therefore, not energy efficient, and can be creating issues in the condensate return system and DA/boiler feed tank

This customer has a recorded condensate return tank temperature of 85 degrees C (185 degrees F). The temperature at their product has never been better and for the first time they are having excess fuel left over on the weekends instead of running out as they usually did.

Can you clarify failed open rate out of the 130 traps installed?

I will have to speak to the manufacturer and come back to you about this. I can only presurme that it is negligable as per the answer above.

I have been selling steam traps for the last 12 years and have had training from all the big brand manufacturers and I refused to believe that these traps worked or worked more efficiently than a conventional trap until I tested them myself. I still believe conventional traps are great products I just believe that these are better.

Are you not interested in taking me up on my offer of a sample trap?

Also, if venturi orifice traps were such poor traps why has Spirax patented one in late 2006? See www.wikipatents.com/ca/2513060.html

Steam,

your comment;

We were given an average running load of 9000kg/hr by our customer which was confirmed by their flow meter.

That can be a problem, because flux can vary greatly. Were as in breaking down the needs with an hour the demand 24,000kg/hr in 5 minutes (400kg/min) and 4000 kg/hr in 15 minutes, (67kg/min)

400kg * 15 min = 6,000 kg

67kg * 45 min = 3000kg

Total 9000kg/hr,

I had a similar problem on a cooker line were the boiler was size to average use, I included diagram of what I mean by it. Only differance your traps could be undersized to handle the loads.

see below, hope you can see it

phoenix911

Hi phoenix911,

I could not really make out the picture but I understand the concept.

I had a look back at our files on the project and see that the 9000kg/hr was not the average steam consumption but rather the maximum consumption. My mistake.

Thanks for the observation though as it is a very important point to bear in mind.

Steam

Ahhh Dweezle - spoken almost like a SS salesperson.

I'm curious, of all the people on the forum who have installed Venturi traps in the past and present, which brands are you using?

I have personally spoken to the fellow from veterans heath admin about the report. When asked why they don't address the fact that mechanical traps also fail closed, he didn't quite know what to say. Bottom line is any trap can fail closed!

In my experience, the whole VA report is held onto by the traditional trap manufacturers as the last chance to save their market share.

There are 100's of thousands of venturi orifice traps installed worldwide by some of the largest multinational companies, saving millions upon millions of $'s annually so why are we still debating if they work???

It is a life cycle value proposition. The traps do not fail and wear out like mechanical traps. Think of the true operating cost of a mechanical trap which based on teh words of their manufacturers need to be replaced between 2 and 5 years after operation on average. What is teh energy cost associated with degredation of performance over the life cycle, which often ends with a failure in open position? Let sbe generous and say that a mech trap does survive 5 years, so over a 20 yr life cycle, you change the mech trap 4 times, and 2 of those times it failed open. Just add it up - venturi traps just make so much more sense, even at 2-3 x's teh price of mechanical traps.

I agree with you and have worked with these types of trap in the last 15 years since retiring from the navy. I have seen some of these types of ventuir traps installed from other vendors which have lasted 25 years and still work the same at 185 psi. One of my customers has ordered for 11 plants and getting ready for more plant. They shared with me data on a process, about 300 psi steam, and the average increase in temperature in front of the trap when converting from conventional trap was about 25 degrees. One of the most mis-understood questions is how can they operate when the steam pressure changes as they have no moving parts. When the steam pressure decreases the pumping ability of the venturi decreases. When the steam pressure decreases the temperature of the steam decreases and the specific volumn of a pound of steam increases. Thus, the decreasing temperature and increasing volumn of the steam means there is less pounds of steam at a lower temperature in the machine transfering energy. The coil or jacket has no moving parts but the heat transfer decreases when the steam pressure decreases and the condensate going through the trap decreases when the steam pressure decreases. The venturi trap and the coil / jacket both have no moving parts but both can operate with modulating steam. My web site is at www.AnchorElite.com . Dean@AnchorElite.com .

Thanks! PS a variable valve and venturi trap are not the same. You need correct dimensions as the steam drops from the higher pressure to lower pressure to make the trap work. If this is not true, why does a conventional trap have on orifice in it. Why not just have the bocket without the orifice?

Dweezle,

Let me first say that I am in no way, form, or fashion associated with any venturi technology manufacturer.

Having said that, it is simply amazing the level of intelligence which you are lacking Mr. Dweezle. Might I suggest that you actually review the data to which you refer before trying to refer to them as "facts."

For example, you state that the Oak Ridge National Laboratory, commissioned by the US Department of Energy, found "orifice type traps to be the least desirable of all the trap types." This is completely untrue. If you had actually read the report, you would have observed that the author made an effort to specifically state that the report was based solely upon the comparison of traditional mechanical steam traps with "orifice plate technology" and NOT venturi technology due to the fact that there was not enough available research and data on the venturi technology to accurately compare them to traditional mechanical traps. (See: Scope & Objective, Page 3, Last Paragraph) It is therefore quite obvious that you either did not read this report or simply assumed that no one else would read this report, therefore allowing you to completely falsify the true topic and results of this report.

Next, you state that "these types of traps are not incentified by rebates..." which is also untrue. Having served as VP of Operations for an international ESCO company for many years, I have been over a multitude of projects in multiple states where there were incentives given for projects utilizing venturi technology.

In addition to your above disregard for "factual information" and the truth, you state that "over time the orifice size increases due to erosion of the orifice and will pass live steam or plug shut." This statement actually makes me want to advise you to seek a refund from whatever "college" you attended based upon the level of education you received, if in fact you received any "higher-level education" at all. Are you seriously asking someone with multiple degrees in physics, chemistry and mechanical engineering to believe that 316 stainless steel erodes and breaks down? Seriously consider asking for that refund.

I could spend a considerable amount of additional time pointing out a multitude of additional errors in your "professional comment on venturi technology" but rather in conclusion will fast-forward to YOUR concluding comment where you state that "the US Department of Energy does not endorse orifice type traps..." May I kindly inform you that it is very unwise of you to make this comment considering the fact that the US Department of Energy does NOT ENDORSE ANY FORM OF "TRAP" mechanical or otherwise. It is unlawful for any federal agency to endorse a product or manufacturer. However, if you are so inclined to debate me on that fact, perhaps instead of pretending to be a "steam expert/professional" you should instead pick up the phone and contact Bill Orthwein (Technology Manager - US Department of Energy - Industrial Technologies Program), John Kimball (US Department of Energy - Industrial Technologies Program) or Steve Goguen (US Department of Energy - Industrial Technologies Program). Or if you really wish to have your facts corrected in a very interesting way contact Joseph Knorade (Department of Energy - Federal Energy Management Program) where I would love to be a fly on the wall during that conversation. In addition, it is obvious that you have no knowledge of "two-phase" flow or physics, otherwise you would have never commented on the venturi technologies inability to "close at the presence of steam." (LOL)

Mr. Dweezle (that name says it all), it is obvious that you are NOT a steam expert or professional, but most likely you are a rep for one of the many mechanical trap manufacturers. Nevertheless, with you obviously being against "orifice technology" I would therefore like to ask you a question, in your "professional opinion." Do not ALL traps, mechanical included, have an orifice? In order for me to save you a few hours of internet research, let me answer that question for you. YES! The fight between the mechanical trap guys and the venturi technology guys have never been about "orifices" but rather about efficiency. Of course, you will probably not be able to understand that concept.

I not only encourage Mr. Dweezle to get some continuing education on venturi technology versus mechanical technology, but I also encourage everyone who reads his future comments to be extremely cautious before taking his comments as "truth." It is amazing what non-intellectual garbage which can come from someone's mouth, such as his. If venturi technology did not work, then why have over 3000 compete facilities, including US Federal Facilities, converted their entire facilities to the venturi technology? Why are ESCO companies such as Honeywell, Johnson Controls and many more, including the venturi technology in their scopes of work for military and federal facilities world-wide?

In conclusion, I also encourage Mr. Dweezle to respond to my comments, but only if he wishes to once again be embarrassed. Trust me Mr. Dweezle. You do NOT want to take this to the next level as bad as I wish you would.

Is it not interesting how all the mechanical manufacturers and their followers sing the same tune regarding the downside to this technology as if it has been taught to them. No new arguments or points to make mention of. Just blind allegiance to the great SXS as they sing their mantra!!

We have just started using a new model of orifice traps on our tracer systems. The orifice traps come with a dual strainer system which minimises our only concern with the older models which is the fact that they could possibly block up from time to time. We have not experienced blocking but because the orifice is so small it was a worry.

The traps work well and they have been doing so for the last 3 years and we see no reason why they won't continue to perform so well. We have taken a few off to check for wear on the orifice but there has been none.

I am not going to use this forum to address your "personal" attacks as they are unprofessional and do not add to the open unbiased discussion.

However, I would like you (or any of the other readers) to present unbiased & professional answers to the following questions:

• Please explain to the readers the specific difference between an orifice trap and orifice plate.
• Please explain the difference between the old orifice technology and the new venturi orifice.
• Please explain the difference between the orifice in a venturi orifice steam trap and the orifice in a traditional mechanical or impulse type steam trap.
• Please explain the primary causes for steam trap failure (regardless of technology).
• Please explain the difference between erosion and corrosion?
• What are the published manufacturer warranty for venturi orifice devices?
• What additional equipment is required to ensure the proper operation of venturi orifice device?
• How frequently do the venturi orifice devices need to be inspected?
• How is the hole in the venturi orifice device accurately calculated?
• How many times does the venturi orifice device have to be replaced/modified in order to have the correct orifice size installed?

"The fight between the mechanical trap guys and the venturi technology guys have never been about "orifices" but rather about efficiency".

There are many aspects to efficiency: Energy; Labor; Operational.

Energy: If a steam trap (regardless of technology) looses live steam it is not efficient. If a failed open steam trap is replaced by one that is not failed, then the energy loss is abated regardless of the trap technology type.

Labor: Regardless of the condensate removal technology installed, some form of maintenance is required AND still need to be inspected for proper operation.

Operational: Improved condensate removal from heat transfer equipment = increased batches, reduced cycle time, etc.

US Department of Energy

The report generated by Oak Ridge Labs IS an UNBIASED report detailing the different type of steam trap technologies and discusses the PRO's & CON's for each type. I encourage every reader to read the report for themselves, which is why I included the link. Here is the link again:

http://www1.eere.energy.gov/industry/bestpractices/pdfs/orificetraps.pdf

Here are some highlights:

"Proper trap selection depends primarily on the service conditions." (pg 5)

"The designers objective for any orifice plate steam trap is to select a small enough orifice to keep too much live steam from escaping and a large enough orifice to keep condensate from backing up." (pg 10)

The Oak Ridge Lab report references the Fluid Control Institute (which is a trade association of steam equipment manufacturers) and has additional information on orifice devices. I encourage all readers to go to the following link & read for yourself.

http://www.fluidcontrolsinstitute.org/pdf/resource/steam/ST101Orifice.pdf

US DOE - Federal Energy Management Program (FEMP)

"Fixed orifice steam traps function best in situations with relatively constant steam loads. In situations where steam loads vary, the orifice trap is either allowing steam to escape or condensate to back up into the system. Varying loads , such as those found in most steam heating systems, are usually not good candidates for orifice steam traps. Before an orifice trap is specified, a careful analysis of appropriateness is recommended". Here is the link for the quote - READ IT FOR YOURSELF & DECIDE.

http://www1.eere.energy.gov/femp/operations_maintenance/om_sttypes.html

"In the case of fixed orifice traps, there is the possibility that on light loads these traps will pass live steam. There is also a tendency to waterlog under wide load variations. They can become clogged due to particulate buildup in the orifice and at times impurities can cause erosion and damage the orifice size, causing a blow-by of steam." Here is the link for the quote - READ IT FOR YOURSELF & DECIDE.

https://www1.eere.energy.gov/femp/operations_maintenance/om_stmaintenance.html

Incentives & Rebates

I encourage all that are interested in identifying local incentives for replacing steam traps (regardless of the technology) go to the following to investigate if steam traps are available for rebate & what technologies are eligible for line item rebate:

http://www.dsireusa.org/

Some locations, if your energy savings potential is HUGE, then instead of a standard rebate, then larger incentives are available. Larger incentives require MEASUREMENT & VERIFICATION (M&V).

For example of rebate vs incentive, in California, an industrial facility can receive a rebate of up to $200 per steam trap OR can receive up to $1.00 per therm saved but need to go through the M&V process.

Two-Phase Flow

For those wondering.....

Hot condensate in a steam system is at (or near - depending on the steam trap type used) the steam temperature. When condensate is discharged into a 0 psig condensate return system the water cannot be hotter than 212 deg F. The hot condensate will instantly "boil off" a percentage of the water mass and become "flash steam". This mixture of condensate & flash steam is two-phase flow.

Closing Comment

As with all tools, there is no one tool that can do every job (just look in your tool box and count how many types of screw drivers, pliers or wrenches you have).

A steam trap is a tool to remove condensate from the system, keep steam in, and ensure the safe & efficient operation of the steam & condensate system. There are a wide variety of condensate removal devices on the market and it is important to understand the pros/cons for each type so that you can make an educated decision as to what is best for each application in your system.

Do not let yourself be bullied or "hoodwinked" by the banter - seek out independent information from the US DOE, Oak Ridge Labs, OIT, Alliance to Save Energy, Energy Star, etc.

I am not doubting that an orifice type trap passes condensate, but since the orifice is FIXED it becomes a compromise of either not passing enough or blowing by steam.

The idea of a custom steam trap is not appealing for emergency replacement needs, unless I chose to keep a lot in stock "just in case" instead of purchasing parts as I need them.

Additionally it would be very difficult to state the trap is energy efficient if it is designed to always blow by live steam - even 1 lb/hr (0.45 kg/hr) under continual duty will waste 8,736 lbs of steam per year (which is equivalent to 1,052 gallons of water, or approximately 87 therms per year).

What concerns me is that the maintenance people at the brewery did not have the steam system knowledge to recognize that there was a problem with the system and either identify and fix themselves, or bring in a steam system expert.

To further confirm system best practices issues, you said the customer is still having "water hammer problem due to incorrectly designed equipment". Water-hammer is a SERIOUS condition, that can, at best, cause a rupture in the jacket, and at worse cause serious injury to personally.

Water hammer in process systems is primarily caused by ineffective condensate removal under low pressure applications, especially where the steam trap is discharging to an overhead condensate return line (either under pressure, or discharging to a vented condensate return pump).

The only solution I am aware of that can effectively remove condensate under all flowing pressures (even vacuum) is an Automatic Pump Trap, which utilizes the high pressure steam upstream of the control valve as the motive force to actively pump the condensate out of the unit, and where there is enough positive pressure, the unit operates like a float trap.

Based on that, it sounds to me like the orifice trap has made some improvements in the operation of the system, due to it blowing live steam during high pressure conditions, but unable to effectively discharge condensate under low, or no pressure situations.

I can only assume that any worldwide trap manufacturer would, like most manufacturing companies, would try to come up with a patented product (even something very close to a copy of their competitor) so that they do not potentially miss the market should the industry be swayed in that direction and the cost of fuel and water are no longer a concern.

However, with the rising cost of fuel, and the continued concern for water conservation, I am not sure how the orifice trap will be best suited for the changing, more energy & eco conscious companies.

Hi Folks,

Difficult to jump in such long discussions. Always end up in yes/no situations and I still believe every system has its own needs to achieve lowest cost possible condensate removal.

Venturi traps do have a point. I've been working with them for over 20 years, and they still last. Regulary checks in the beginning did not show any erosion or enlargement from the venturi itself. Does not mean I want to start a discussion as if they consume much steam or not, but if they would leak such big amounts, the internals would been enlarged long time ago already. And don't need to explain what steam erosion does in an open failing trap...

Don't worry so much about the orifice size towards the load. It is not like 'or blowing steam' or 'remove condensate'. It is always both. And well designed it seems to perform in the total range of the applications. Besides this is logical due to the steam control valve opening for more heat, so pressure rises and more steam enters = more condensate to be removed. Since venturi capacity is pressure dependent, this is OK. Seems logical to me. And the same in the other direction: less heat demand, valve closes, pressure drops venturi capacity drops which corresponds with the less condensate to be removed...

And now you might say: Oh, but I have an appplication with no condensate sometimes and then it will leak steam... Just check if your steamvalve is open or not at these moments... Closed? OK don't worry, no condensate is removed , and no steam can leak.

Of course we know batch processes with full condensate loads in beginning and little at the end. Agreed, but the average between no loss in beginning and bigger but acceptable loss at end is still neglectible in total. Main advantage is the absence of moving parts to fail, and therefor the process keeps on going...

To be honest, it is not my concern if venturi traps have a bit steam consumption. I'm definitley sure all systems consume energy. Besides, ever seen a floating trap swilling 65.000 kg/h condensate as a calm flow without any steam passing the internal valve? Be sure inside it will feel as a hughe wirlpool, and definitely steam will pass toghether with the condensate, same as for orifices.

Main problem with mechanical traps is that they will fail, tomorrow, next month, next year... and all you can do is look at it and spent your money on checking and replacing them (and on your energy bill for the period they leak... and I got sick of the uncertainty and checking them weekly...).

Good luck to the non-believers - and do keep on filling the money sacks from your trap suppliers, because this is how they educate you.

Better focus on how to get rid of this brain twister, because once you did let them in, you keep on spending money on replacing traps, and they obviously will help you with check-up tools and programs to do so as quick as possible... nice turnover for them... not from me anymore...

Orifice works well with stable process condition such as condensate flow rate or pressure and you size it properly. A manual valve works the same!

If you have already had a control valve, you have no need to use any trap. The control valve will handle the job.

I would like to share with you the basic of Trap, Valve and Orifice...
- Orifice is a FIXED hole
- Valve is a VARIEABLE Orifice
- Trap is a type of Valve which is Varieable Orifice. Some types of trap is On-Off, some traps are modulating.

Again, Orifice is FIX. Hence, you can use manual valve to handle the job and get the same result. Furthermore, when the process condition changes, you can adjust the manual valve accordingly- no need to change likes the orifice trap!

Thank You
Veera, RI

Dear guest Veera, just to clear my mind - if you mean manual valve or automatically, guess you meant to install it at the same location as the trap or orifice, so after the application, right?

If so, this works also properly. But seems to me you need to close it a bit more to dam up a bit condensate? If not, wouldn't there be a lot of life steam going through?

(this is what we did on level controlled vessels where the high-low level steered the valve on the outlet and the presence of too much condensate avoids steam waste)

Don't see directly how to drive an automatic valve on the outlet with no flooding condensate in the application? Seems to me it always will loose steam?

One thing to look at is on very large systems, make sure you drain the system during start-up to avoid water hammer.

We work with these traps in the South Eastern USA. I used them when I was in the US Navy.

Contact Dean@AnchorElite.com

Sincerely,

Dean

which venturi steam trap you used? there is a number this type of trap available on the market.

We are using the Delta Industries brand. See www.delta-industries.com

How does a venturi trap react to super heated steam? Can it well enoughb lock the steam to pass trough? If so, I guess this should be a very small venturi, right?

suppose 600lbs - what's the size then?

I would not recommend venturi traps on a superheated application as there is no condensate to plug the orifice.

These traps can be used in superheat lines. When the steam line goes to superheat, the specific volumn of a pound of steam increases thus chocking the steam flow. I.E. with superheat, the chocking is done with the increasing specific volumn of steam and not condensate. Care should be taken in start-up with venturi traps sized for superheat. Dean Trytten www.anchorelite.com dean@anchorelite.com

Just some clarification points on superheated systems. When the system first starts up, it is NOT superheated, and the warm-up load to heat up the pipe/system is very high. Once the system is up & running, and has reached superheat there is no more condensate.

An orifice device has a fixed orifice with no ability to close off at the presence of steam (or lack of condensate in this instance). So - if it is a fixed orifice:

- How well does this trap deal with the high warm up condensate load? I expect if the orifice is "engineered" for the superheat conditions, it will be too small to discharge the high volume of condensate needed during start-up.

- How exactly does this trap NOT leak SUPERHEATED steam into the condensate return line? I expect if the orifice must be so small as to not allow superheat to escape into the condensate return system, then it cannot handle the start-up load. If it is larger to handle the warm-up load, then it would be too big for the superheat conditions and pass live (very expense steam).

A previous blogger stated that you have to be careful with these traps because water hammer is an issue with these traps if you don't drain the line first. A steam trap's job is to remove condensate from the line under all flowing conditions and not pass live steam. If the orifice devices back up condensate and require manual draining, then they are not doing their job.

To read more on the dangers of water hammer:

http://www.kirsner.org/pages/articlesAlt.html

For those that want to safely operate a superheated system and not leak steam under superheated conditions, and discharge condensate under warm-up loads, I would recommend either a thermodynamic steam trap, or a piston style steam trap.

Hi,

from my point of view start-up on big pipe in steam systems (saturated or superheated) could never be done without operators! Fast and automatic start-up of such big systems is always a danger for operators and valves installed on the pipeline.

This is the reason why steam traps must to drain condensate in operating conditions but start-up have to under control and by manual operations. Above all on refinery where start-up happen maximum once a year.

Venturi traps are really fine and in the photos in attachment at the BP report show a thermodynamic steam trap as you suggested! May be these are not the best choice!

As the drip leg remained closed for steam trap failure, this could not happen with Venturi steam trap.

Hi Bryan,

It's good to see your message on the post. The picture shows the replacement trap seem to be a venturi orifice trap.

With regards to the potential blocking the orifice venturi steam trap. Any steam trap do require a regular check up and maintenance and orifice venturi steam trap is no difference to any other traps where check up and maintenance are required but with minimal attention. Traditional orifice trap can only handle a fix condensate load but with new orifice venturi trap, it's unlike the traditional orifice trap, it works with varying condensate loads with unique design orifice.

If there is any question, please do not hesitate to contact me on lawrenceyw@hotmail.com

Regards

Lawrence