Centrifugal pump explosions

No yet thanks goodness. But In my opinion will be good to first obviously use an spark/explosion proof motors around and install some kind of pressure relief to by-pass back to supply tank or to some good spark/explosion proof vessel providing properly designed loop for such purpose just in case as a way to relief back - up pressures build out of safe range overthere. Also provide for a well ventilation equipment for hazard enviroment conditions all together.

Also will be important to have a fire supression monitoring system set up just in case. Anyway your engineering people will come on with best approach eventually anyhow.

Lock and Tag,

MC

A positive displacement pump will break if pumping against a blockage, but not the centrifugal as stated. The discharge pipe would give way before the pump casing most likely as it is weaker.

How can you say the piping will break before the pump? The pump may have a MAOP of 1200 psi and the piping and flanges 1480, can you gaurentee the piping will burst first.

This is why we install PSV's set at thje lower of the pump MAOP or the piping.

I didn't say "before". Discharge pipe is after pump.

let me rephase, how can you say the piping anywhere on the system will fail before the pump will fail. My previous post the word before was in reference to prior time or event, not before meaning upstream.

In the paper industry, pumps or refiners (wood fiber processing equipment that act somewhat like grinders) both can explode if operated against a dead head. The temp rises as pump energy goes in faster than head dissipates, then when steam is generated, equipment can explode.

And this is with non-combusible materials. Any liquid with heat sensitivity is something to be cautious with, of course.

I've also worked with pumps in explosion-proof environments where any spark will do the job.

Be careful out there.

Your pump should be fitted with a bypass valve all fuel pumps i have worked on have had iether a bypass back to tank or an internal bypass valve as part of the pump Gilbarco bennet pumps etc all sell them the smallest pump being for refuelling cars etc up to 6" models for bulk dispensing. it is a basic spring loaded valve beteen the inlet and outlet when the pressure reaches a set reading the valve opens and the product recirculates until pressure is reduced by opening refuelling nozzle etc. Never heard of a pump exploding, unless a seal goes and the fuel leaks from the pump exposing the fuel to an ignition source.

I've seen centrifugal pumps break open. The cause was always the same, someone fed the relief pressure back into the inlet. As centrifugal pumps raise the pressure by a set amount, by increasing the inlet pressure ( by feeding in the outlet line) teh pump increases teh pressure exponentially, blowing up the weakest bits. Normally couplings, seals etc tend to leak first limiting the damage.

To avoid the above enure the pressure relief fluid feeds back to the tank or the pressure is removed prior to admission to the inlet.

Bingo. I've seen it as well on a hot brine system where the discharge piping was fibreglass. That stuff fails catastrophically. The stuff was metered anyway and they had motor amp indication, so a simple low amp/low flow cutout would have saved a great deal of damage. They added a high casing temp input and tripped on any 2 of the 3 variables going out of range to minimize nuiscance trips due to flow metering issues.

I remove old underground tanks for customers often and I use a small 12 volts pump to move 300 to 500 gals of kerosene and never had a problem. You must be pumping a lot of be in a real hurry to use such a large pump.

The blocked pipe (High Pressure) situation has been well covered. I would just like to add that I would be very concerned about cavitation within the pump casing.

With the reduced pressure you could well get vapourisation and a heat build up.

Not a good combination with combustible liquids.

BAB.

We have been moving bulk IPA (isopropyl alcohol) for many years. Yes it is an explosion proof set up. But we have no reliefs in place. The pump itself is an aluminum housing but the impeller drive is magnetically coupled. It has the ability to over come the head pressure but if there is a blockage or dead heading (valve closed off) the pump motor can free spin and the pump will not over pressure or cavitate because it can stop with out burning up or exploding. Theses set ups are a little higher in the beginning but they will not require all the extra cut off stuff.

Have you given thought to use of a "jet pump" to move the fluid. These pumps are often employed in aircraft fuel tanks to move fuel for balance purposes.

OOOHHLYYyyh...! Now this is really steam-up with a Full Throtle of knowledge here at CR-4 corner definetly. I knew it you guys have the technology. For Sure. I'm telling ya' after reading all this comments anyone may become an expert at some grade no doubth about it. Nice feedback in a flash.. waaoouuh!

Nice Deal Pal's,

MC

Geoff

I did extensive research back in 2003/4 and put a presentation together. I believe I was the first person to document the phenomenon. I presented it at the International Hydrohoisting Conference in April 2004 in Santiago. The pump explosions I studied are non-chemical. Here is the link and hope it can be of some use to you.

http://www.amre.org.za/downloads/seminars/16March2006/Pump%20explosions%20Amplats.pdf

Best regards

Brian