Pressure drop/increase by consumption decrease/increase

by Ali Demir
(Istanbul-Turkey)

I have a main compressed air supply line at 6 bar pressure. I installed an air pressure regulator to reduce the pressure to 1.5 bar to release from 6 points (ends) after the regulator.


When all ends are open the pressure is set to 1.5 bar. As soon as I close one or two or more ends the pressure after the regulator increase to 1.7 to 1.8 bar. What is the reason for this?

I want the pressure remain the same at 1.5 bar independent of the consuming ends.

Comments for Pressure drop/increase by consumption decrease/increase

Click here to add your own comments

Aug 10, 2016
Regulator problems
by: Bill

When you dial the pressure setting down on the regulator Ali, are you hearing it relieving?

What size are the air lines to and out of the regulator.

Are you confident that the regulator has the flow capacity for the flow required by your applications.

If you are hearing relieving, if your regulator is the right size, then you may need a precision regulator and gauge to get the accuracy your application requires.

Aug 10, 2016
Increase/decrease of pressure
by: Ali Demir

Bill,

Yes, when I mean "end" I do mean "outlet"

Thank you very much for your valuable comment. I have made the following trials;

1. I set the regulator to 1.5 bar while all 6 outlets were open/on.
1.1 As soon as I closed/put off one outlet, the pressure indicated rose to 1.54 bar
1.2 When I closed/put off the second outlet, the pressure indicated rose to 1.58 bar
1.3 When I closed/put off the third outlet, the pressure indicated rose to 1.60 bar
1.4 When I closed/put off the fourth outlet, the pressure indicated rose to 1.63 bar
1.5 When I closed/put off the fifth outlet, the pressure indicated rose to 1.91 bar

In reverse order,

2. I set the regulator to 1.5 bar with one outlet turned on.

2.1 As soon as I turned on the second, the pressure indicated dropped down to 1.43 bar
2.2 When I turned on the third outlet, the pressure indicated dropped down to 1.39 bar
2.3 When I turned on the fourth outlet, the pressure indicated dropped down to 1.38 bar
2.4 When I turned on the fifth outlet, the pressure indicated dropped down to 1.36 bar
2.5 When I turned on the sixth outlet, the pressure indicated dropped down to 1.35 bar.

The upstream pressure has always been 6 bar.

I still could not solve the problem. Can you please help. If the problem was due to non-relieving type of the regulator, the pressure should not have decreased while the number of outlets were increased.

Regards,

Ali





Jul 22, 2016
Line pressure increases
by: Bill

By ends I take that to mean outlets?

If your regulator is set to 1.5 bar (about 23 PSI) and you are getting 1.5 bar at all outlets when they are open, there is no justification for the line air pressure downstream of the regulator to those outlets to increase when any of the outlets are closed... unless...

For some reason by closing the downstream outlets you are getting a small pressure spike back from those air using appliance AND your regulator is non-relieving.

Check to ensure that the regulator is of the relieving type, as they are supposed to relieve any downstream air pressure that is higher than the regulator set point...

AND - a general purpose regulator may not have the pressure-setting level precise enough for you. I understand that the typical general purpose regulator may have an accuracy range of +/- 3-5 PSI, and that would account for the discrepancy you see.

You may have to invest in a precision regulator with much tighter setting tolerances.

Click here to add your own comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Compressed Air Regulator Questions.