Air compressor working pressure

Oi! Keep the noise down! Some of us are trying to get some kip! <Cough, splutter, wheeze.>

Either the compressor, or the pipe connecting it to the air reservoir, or both, is/are undersized for the duty.

We can probably narrow it down even further. If the pipe is too small, this would only aid in the pressure remaining high. Ergo, the compressor is too small. Alas, no data are given as to compressor cfm vs loads cfm....

The original poster's pressure gauge is on the reciever, though.

HI:

Please check with the air compressor book, what kind of gear did the manufacturer installed at the unit.

Possibly they had install the wrong gear between motor and compressor unit.

Good luck!

Isaac Raz

Thanks you for the post.

Hi guys, Im a newbie. Nice to join this forum.

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I agree with PWSlack. Your Compressor & pipelines undersized. What is the capacity of your 30 Hp compressors in LPM/CFM/m3/hr ? What are your total air load requirement in lpm/cpm/m3/hr ?

First - Wheather the pneumatic reamer is working perfectly with 4Kg/cm2?.

If yes, nothing to worry about.

The pressure gauge may be re-calibrated. There are chances of it showing a wrong reading.

Name plate is saying working pressure as 7Kg/cm2. But nothing wrong in working at a lower pressure.

If No, then you have to increase the pressure. Check the rating of the compressor and whether it can meet the requirements.

Parthasarathi Dalai, Bhubaneswar

You have not given rated flow rate of your compressor and type of compressor you have. It must be available in same name plate. Working pressure is normally at rated flow rate and at the discharge flange of compressor. If you draw more air than its rated capacity, pressure is definetely going to drop. So please check how much air (in CFM or Nm3/hr) you are consuming against how much your compressor is rated for?

If you are consuming less flow rate than rated & still getting low pressure, further analysis may depend on type of compressor.

working pressur mentioned on the reciver 7kg/cm2 is its working pressur, above that safty valve will blow. find out what what is the pressur & volum of air requried for working of reamer

The most important piece of info you dont provide. What is the cfm requirement of the tool, and what is the cfm rating of the compressor? If the gauge drop so badly the working volume of the compressor is too small. Any compressor must be able to maintain the rated cfm of the tools.

the answer to your question is "yes". Ideally, the gauge should show the plated working pressure when in use.

The gauge should show plated working pressure when there is no load (reamer and all other air operated equipment is not in use). When you do start using the equipment, eventually the pressure will begin to drop, but the compressor motor should start-up to get the pressure back up to working pressure. The longer it takes to get back to operating pressure, the longer the compressor motor will run. If the gauge shows 4kg/cm2 when the reamer is operating, then you should notice that the compressor motor is continuosly running while the reamer is in use.

First question, why was a 30 HP compressor installed? Why not a 15 HP or 50 HP compressor?

How much air and pressure doe the reamer need? Does it work fine at 4 Kg/cm2?

Sometimes vendors will use cheap pressure gages on equipment that do not work well after the first week. Is your pressure gage accurate?

What is the setpoint of the compressor pressure switch or control? If that is set too low, carefully reset it to the correct output pressure. Setting the pressure too high is just a waste of electricity. It should be set about 5% higher that the required pressure at the farthest piece of connected equipment.

As other posters have suggested, the demand and duty cycle of the reamer must be identified in order to answer the question it appears you are asking.

The pressure gauge on the receiver shows 4 Kg/cm2 because the air is being drawn off faster than it is being replenished by the compressor. If the duty cycle ends and the compressor continues to run, it refills the receiver until the pressure again reaches 7 Kg/cm2. If it is not a continuous duty and the reamer draws off the receiver (stored air,) the compressor may be suitable.

If the question you are trying to ask is 'is the compressor and receiver properly sized' you have not provided enough information. If you are, in fact, asking whether the pressure gauge in the reservoir is correctly showing a different reading from what the compressor rating is, the answer is 'probably.'

Agreed, several posters have made this point. OP Trichy Boobalan hasn't come up with the information. C'mon Trichy, we're trying to help, answer the questions and we may be able to do more!

Codey

If the air is drawn of faster then :

1 . He should get a bigger compressor or

2 . Have a bigger receiver. This will solve his pressure drop problem.

It is more economical to operate a a lower pressure so then he should have a pilot-operated PRV set at 4 kg/cm2 with inlet 7 kg/cm2. (Then again if he does not know the output flow cfm/m3/hr he would again face problem of oversizing/undersizing of the pRV)

By the way since he is gone so let us tell each other.

Ducon, "2 . Have a bigger receiver. This will solve his pressure drop problem."

Ducon, I have seen too many of your posts to know that you really did not mean this the way it sounds! A bigger receiver will NOT solve the problem of pressure drop, it will only moderate and level out the pressure swings from the process. If the process is cyclical, a small compressor matched to a properly sized large compressor can serve a larger load.

The receiver does not create pressure, but it can store a volume at a sufficient pressure IF the load is cyclical and IF the compressor has enough time to recharge the reservoir in between cycles.

I know that is what you meant. Just buying a bigger receiver does not solve the problem, the application needs to be reviewed to balance the supply source and the user deamnd to balance the system.

There are a few questions unanswered:

1. What is the pressure in the reservoir before starting to work on the reamer? If it is 7 Kg/cm2 and if the pressure is gradually going down while the compressor is working one must come to the conclusion that the reamer air flow is more than the compressor capacity.

2. Does the pressure guage remain steady after coming down to 4 kg/cm2? If yes, then the air flow to the reamer is gradually reducing till it becomes equal to compressor capacity. In this condition if the reamer is performing satisfactorily, perhaps you don't need to bother.

cheers