How often does an air compressor typically run?

[acb324]

How often does an air compressor typically run on a dry system? I understand that over time the system leaks more and it will run more frequently, but at what frequency would a red flag go up for you?

I am having reports from a building engineer that the compressor on his dry system is running 6-12 times a day. He was guessing, but it is evident to me that this thing must be running pretty darn frequently.

 

[cdafd]

Enough to keep the system from tripping.

How about run a test. Shut the compressor off, mark the air gage, watch it the first hour to see what kind of pressure drop there is, and decide from that how long to continue the test.

From the test decide how fast you are losing air and if you need to do anything about it

 

[stookeyfpe]

Well it sounds like something is leaking to me. I would pull the highest sprinkler, install a pressure transducer with data logging features and a independent thermocouple with data logging capability so delta P due to delta T is excluded and see what the losses are.

 

[chicopee]

NFPA(fire) Code Issues should have been the site to pause your question as someone would have cited an NFPA code.

 

[chicopee]

Oops I goofed.

 

[acb324]

Thank you for the great suggestion Stookey. I was thinking it was running too frequently and it was an abnormal amount of leakage. I will forward the idea on.

I don't have a good feel for how often a compressor runs on an old dry system. I am a design engineer so I only see them right after installation when I go to a site to do construction administration, or during an assessment like this. I have never encountered a compressor that ran more than once during the time frame of a site visit.

Realistically, they have a dry system installed completely within a heated area so I am suggesting to them that the whole thing be reevaluated for this reason and a few other non code compliant items. I wanted to say that from what little info I have the system would appear to have some decent leakage, as an additional item to bolster the case.

 

[Lamuppet]

I don't know if the client Will like this, but here's a part of the code:

NFPA 25 2011 - art. 13.4.4.2.9  Dry pipe systems shall be tested once every 3 years for air leakage, using one of the following test methods:
(1) A pressure test at 40 psi (3.2 bar) shall be performed for 2 hours.
(a) The system shall be permitted to lose up to 3 psi (0.2 bar) during the duration of the test.
(b) Air leaks shall be addressed if the system loses more than 3 psi (0.2 bar) during this test.
(2) 
With the system at normal system pressure, the air source (compressor or shop air) shall be shut off for 4 hours. If the low air pressure alarm goes off within this period, the air leaks shall be addressed.

 

[cdafd]

Lam!!!

Someone actually reads the book

Thanks was having trouble finding a ""pressure transducer with data logging features""

 

[ForestWilson]

This should be troubleshooted.
Very common to have a defective check valve on the compressor or air supply line, causing pressure to drop and trip the pressure switch.

Also, the pressure switch should be on the system, not the compressor or upstream of the check valve.

 

[fireguy519345]

http://www.microdaq.com/monarch/data_loggers/pressure-logger.php

http://www.dicksondata.com/products/PR350

Try these sources. If you try one, let us know if/how they work to resolve your problem