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Industrial Air Compressor

07/19/2010 8:56 PM

Hai Guys, I'm setting up a air compressor room which suits a 100HP and 50HP vane type air compressor.My question is when we install the pipeline in series, which mean that main pipe as 3" in size will be getting in 2" pipe and 1 1/2" connection into it.I'm afraid that will there be any resricted in flowrate because the 100HP compressor using a inverter type and we do comes across inn situation where the 100HP pump in 7.5bar of air and 50HP compressor do pump 7.5bar of air and and the result is the 50HP compressor were off load for few minutes.Is there any sort like the air pressure are lagging each other.For you guys information the flowrate of the 50HP is 200cfm and the 100HP is 400cfm.Please advice..Thanks.

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Guru
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#1

Re: Industrial Air Compressor

07/19/2010 9:32 PM

If you want the compressors not to interfere with each other, one way is to feed the outputs each in a different storage tank with good anti return valves.

You can have a outlet of each tank, (even adjustable- or a pressure regulator) feeding your pipe line.

Best is to have tanks with a volume resp. to each compressor's air production.

If you do not need both at the same time, when less air consumption, you can set priorities with the pressure switches.

The hysteresis will be minimal.

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#2
In reply to #1

Re: Industrial Air Compressor

07/20/2010 1:58 AM

These are PD machines - they have no idea where they are pumping to. They will deliver a given volume to wherever at whatever pressure the system is at.

Why would you then need two systems?

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Guru
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#3
In reply to #2

Re: Industrial Air Compressor

07/20/2010 2:50 AM

What I read is 2 compressors, connected to one air net. Vane - what I have interpreted as screw types. We have such a set-up in our factory that has also a 100 HP and a 40 HP compressor, both feeding the same net. We had the 40 first but later when the factory expanded, we had to add the 100 HP. Maybe you can elaborate your standpoint or interpretation? I may have understood the question wrong, but I understand that the 100 HP makes the 50 HP work in oscillating way. Of course I might be wrong. Regards, D.

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#4
In reply to #3

Re: Industrial Air Compressor

07/20/2010 3:12 AM

I also do not understand the problem.

"the 50HP compressor were off load for few minutes.Is there any sort like the air pressure are lagging each other"

Please would the OP clarify this statement. What is actually happening?

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#7
In reply to #4

Re: Industrial Air Compressor

07/21/2010 5:22 AM

Imagine,100HP air compressor connected to inlet port of receiver tank (2000llitres),going outlet into a drier inlet port and finally going out to main line (production).The same goes to 50HP,into a tank (1000litres) but the oulet of the tank (1000litres)are sharing with the oulet line of the 2000litres tank.Got the view?So when I say lagging, it more a less means that when this two compressor are working,of course the 100HP is working hard than the 50HP because different flowrate and what we have in final,the 50HP compressor off load....means it switch off automatically.

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Guru

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#8
In reply to #7

Re: Industrial Air Compressor

07/21/2010 7:16 AM

What is the pressure setting on the 50 hp compressor? Is it lower than the 100 hp? If so, the 100 hp will cause the 50 hp to reach turn-off point.Which begs the question, do you really need both compressors all the time, or does the load vary?More information will help us to help you with your problem.Perhaps a sketch including pressure switch settings, all check valves in system, all receivers, etc.

HTRN

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#9
In reply to #8

Re: Industrial Air Compressor

07/21/2010 7:53 AM

Pressure setting for the 50HP is cut in at 7 bar and cut out at 8 bar.The 100HP whereas cut in at 7.5bar and cut out at 8.5bar.But remember that the 100HP unit is a inverter type and it works depends on how much air pressure in the tank.For example,if the tank pressure is 8.5 bar,the compressor will keep running in but at low speed and the speed varies if the pressure drops.The 50HP unit is a fixed speed and once the pressure increase to 8 bar,it will off load means the compressor run in idle without pumping out the air and after 3 minutes its stops.

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#10
In reply to #9

Re: Industrial Air Compressor

07/21/2010 8:49 AM

I still do not understand why you think you have a problem (maybe I am just being a bit slow).

The 100 HP variable speed machine (you do not say at what pressure this machine is designed to control at) will run continuously at varying speeds in order to maintain the pressue at some set pressure, say around 8 bar. Only if the pressure drops below 7 bar will the 50HP machine cut in. The 50 HP machine will again cut out at 8 bar while the 100 HP machine contiues to run. So what is the problem?

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#12
In reply to #10

Re: Industrial Air Compressor

07/24/2010 9:24 PM

I've checked the design of the propipe pipeline flow.From the outlet of receiver tank for the 100HP Compressor, there is a 'T' joint connection for the 50HP Compressor from its receiver tank outlet pipe to joint together with the 100HP pipe.What happen is the 100HP cfm is 400 whereas the 50HP is only 200 cfm.Would I say due to the high flow of the cfm from the 100HP can cause a restricted flow from the 50HP compressor air to come into the 100HP pipeline and hence make the 100HP to work harder than the 50HP?And it do make sense that the speed of the 100HP compressor fluctuates till 1800rpm and min speed at 1200rpm but remain a pressure at 7.5bar and this time the 50HP compressor were off load and no air is pump in.

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#6
In reply to #2

Re: Industrial Air Compressor

07/21/2010 5:15 AM

We only have maximum 100HP vane type compressor in our product and the production line required 200HP.Currently we manage to install the 100HP as a new unit and the 50HP is a used compressor.Due to higher in air demand, we have to set up in these way as 2 system but end up in a disaster..

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Guru
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#13
In reply to #6

Re: Industrial Air Compressor

07/25/2010 3:47 AM

When needing 200 HP and providing 150 with both compressors, means to me you are 50 HP short. If you want the 50 HP to run continuously, just set this pressostat e.g at 1 bar or more higher than the 100 HP. It will save you money, because starting the 50HP all the time is more expensive than letting the 100HP shutle between your two speed limits. You can also put a anti-retour valve between the two tanks, so that the air of the 100 has no access to the 50 - But if the 50 can build up enough pressure, it won't be necessary- also a regulator at the output of the 50HP tank can do the work, or a proportional valve with some (or your) intelligence setting.

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#5
In reply to #1

Re: Industrial Air Compressor

07/21/2010 5:11 AM

I do agree on the installation of different receiver tank for each compressor, and not sharing but the situation is both compressor do have their own receiver tank, as the 100HP connected to 2000litres tank and 50HP connected to 1000litres tank.Now the outlet of the both tank are connected sharing same line as 2" pipe going into drier inlet before heading to the production line which uses 3" pipe.We might have to do something on the connection of the pipe which doesn't let it to be shared instead of performing separately but have to go through the same main line.Any idea?

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Guru
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#14
In reply to #5

Re: Industrial Air Compressor

07/28/2010 8:23 AM

You have absolutely no problem. Only thing I can suggest is to replace 2" pipe with next higher size because velocity is high at full capacity.

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Anonymous Poster
#11

Re: Industrial Air Compressor

07/21/2010 1:18 PM

The Guest is correct. There is nothing wrong with your system as it is currently set up. The optimal running condition will be the 100 HP compressor runs continuously and the 50 HP cycles on and off as required. If you disconnect the compressors from each other both will cycle on and off.

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