Any air experts? air ammeter needed

Ian, sorry I missed your earlier post about the eBay rotameters you bought. Surely one of those plumbed to push-fits with the valve fully open will be perfect to detect even 1/50 of a CFM flow?

Andrew.

Andrew

yes i hope they will work its just they only rated at 100 psi rather than the 150 psi likely

Also the meter will not be left in place its just for fault finding purposes

most of the time the whole system works in spite of leaks... the first time problems flag up is when the compressor packs in because its running 100 % of the time

A big leak is obvious because one unit wont work or one actuator fails to move..its just lots of small leaks that build up to a massive air loss

If this is nearly new, cost millions and take hours to gain access its obviously not fit for purpose and I would send it back!!!

Seriously though, I'm flabbergasted that such a complex bit of kit does not have built in diagnostics. For something that is a fundamental part of an industrial process running continuously I would expect numerous temperature sensors, bearing vibration monitors and miscellaneous other transducers so that the health of the machine is always known.

As to the covers being so time consuming to remove, they are obviously in the wrong place. Are the covers to stop people trapping fingers or purely decorative?

Ian P

This is the type of press

the panels on each side on a kba are made of 10mm thick alloy those are the white door size areas near the top

under there is the control systems of the machine

the air supply pipes and control valves are under the running boards

So imagine being called in to fix a problem with this when the operator tells you the hp compressor is running all the time and kicking out due to overheating and having to find the problem quickly while 3 blokes stand around doing nothing and a factory full of machines all making lots of noise

Hi.

At work we used an ultrasonic leak detector. Our compressor room if extremely noisy with 7 large oil free 2 stage compressors screaming away. It comes with noise cancelling ear defenders which connect to the detector.

The detector itself has some sort of crystal in the end which becomes "excited" when in contact with an air leak. This the actually gives you a totally individual sound of each leak. You can even get a rough idea of the size of the leak, it sounds that good. It will also guide you to the leak if your in the rough area, as the crystal becomes more excited you will hear the leak becoming more intense.

I'm NOT connected to this manufacture in anyway, its just a useful piece of kit we use. I'd imagine that you would have to take all the panels off anyway to attach a "meter" of some sort.

We've found loads of leaks all over our site, ones that you wouldn't hear or feel before. Hope this helps.

Ben.

What about a bit of uv dye put into the airline, same method as aircon leaks in cars? Hell of a lot cheaper than fancy detectors, 20 quid would buy the dye and torch.

Hi Ian

Sounds like you need the equivalent of a leak down tester, used on engines to test for cylinder leakage.

Basically it is an orifice ( in the case of cars they use 40 thou) with a pressure gauge either side.

If you plumb the tester in at A in your diagram, and there is no air leak or flow both gauges will stabilize to the same value, the more flow the greater the difference in the gauge readings. So if you can either turn off all the valves and open one at a time to find the greatest pressure drop, or have them all open and shut off one at a time to find which one makes the biggest difference.

If you have no idea what size restrictor orifice to use between the two pressure gauges, you can put a shut off valve in, and use a bit of trial and error to get a meaningful reading.

Because it is only a comparison tool there is no need for absolute accuracy or calibrated gauges, you are just comparing the flow through the machine against the flow through the restrictor, and if it is significant it will show up as a pressure drop.

Hope this helps

Trevor

I have sorted the problem now with the flow meter bought off ebay

I tried it on my compressor in my workshop connected up at 150psi for about an hour ( gauge rated to 100psi)

It seems fine its solid acrylic 1" x 1.5" with 2 tapped connections,I'm not sure what would happen if it failed coud it explode with shards of perspex eveywhere?

Anyway on connecting to the machines supply it was a simple matter to isolate each unit until one was apparent it was consuming lots of air at rest so panels off and the leak was obvious.so good result with lots of time saved

after repairing the leak the flow meters ball was just off its rest at the bottom rising fully to the top if I actuated one valve so its nice and sensitive ( the scale is marked at 0-20 SCFH )

Ian

Ben how much roughly is that skf gadget?

Hi Ian,

The SKF detector is about £900 +VAT from what I can see online. There might be a newer one out now or something but that's the price that's online. I wouldn't want to drop it .

Ben.

Hi Ian,
How about using a water flow meter. Although they are designed for water I cannot see why they should not work with compressed air. (The calibration would probably be wrong but I suspect you only need a comparative reading.) They work by the flow rotating an impeller. If my conversion is correct then 4 cu ft per minute would be 113 litres per minute so one like this would probably be OK

**LINK**

They are rated at 2 megapascals which is 290 PSI

The output is a frequency so you should be able to find a digital multimeter that has a frequency range to display the output. It would also have the advantage that you could have along lead to the display so you could see the result of opening and closing valves to isolate sections of the machine.

Les.

Les

that looks great i'l order one of those to play with

Ian

Hi Ian,
Overnight it occurred to me that the 4 cu ft per minute may be the free air delivery rating of the compressor. (Rather than the volume of air per minute actually at 150 PSI) If this is the case then the actual volume of air at 150 PSI would be about a tenth of this. (0.4 cu ft per minute or 11.3 litres per minute.) If this is so then a smaller flow meter would be more suitable. If you search on ebay for "flow meter" you will find many flow meters that amy be suitable. You can also find "ultrasonic leak detectors" on ebay.

Les.