Question Hydraulic Test Ports for local or remote gauge-points and possibly controls?

[-JD-]

(Some of you may have seen that while I'm SLOWLY going over and cleaning up my 20 year old (seemingly, almost-pristine) RIX SA-6AG and preparing to fire it up, I'm planning for the future. While I will probably create a specific unit/build thread, I have some more generic questions that are not "type", much less unit-specific, so I think deserving of their own threads ...)

One of the things I see frequently is that one of the best compressor diagnostic and monitoring tools it to check the pressures at the various compression stages. Big fixed units seem to frequently have these, but portable units general don't. I'm going to be re-plumbing mine to allow access. An option I am strongly considering is to allow either easily disconnectable and/or remote gauges, to minimize damage from long-term vibration and handling of a portable, open unit. That might also be tied in with a demountable fill panel (a topic for "someday").

In nosing around for various solutions, ranging from paintball QDs, to AN or JIC connectors, I stumbled across "M16x2" test-ports used for hydraulic systems that can be safely connected and disconnected under pressure.

They are fairly reasonably priced and available with 9000 psi rating, Viton seals, in zinc/nickel-plated carbon steel ($11- TPPM1620CVN1/4 : Anchor Test Point, 9000psi Rated, 1/4" NPT, Viton Seals, Zinc/Nickel Plated Carbon Steel) or in SS ($37- TPPM1620SVN1/4 : Anchor Test Point, 9000psi Rated, 1/4" NPT, Viton Seals, Stainless Steel) - Model Specs (https://onehydraulicsdata.s3.amazonaws.com/DATASHEETS/TestPointBrochure_May2020_Digital.pdf).

Rigid gauge-adapters (Test 20 x 1/4) and Microbore style hoses (M16x2 X NPT Test Hose) are available in multiple lengths with 1/4"-NPTF on the other end for direct gauge connection or adaptation to plumbing on a remote panel.

• What thoughts do y'all have on the concept?
• Concerns if I stick to < 40%?
• Can I reasonably get away with zinc/nickel-plated carbon steel or do I need to go with SS for the fixed test points since they contact the gas-flow path?

ETA:
Well I went down the rabbit hole and after an hour+ of searching I found that despite being a relatively well known plating option ON stainless steel, zinc-nickel, is evidently still highly galvanic with stainless. So I am guessing the answer to my 3rd question is "Probably should pay 3.5x for the stainless fixed points" if I am going to be screwing it into stainless NPT fittings.

 

[Cio]

Measure temp. Temp will tell you more than pressure will.

 

[iointerrupt]

I doubt it makes sense financially.

You aren't going to be plugging in high-dollar precision gauges. The gauges are just there to tell you "yup, this is in a reasonable pressure range".

As such, for the price of all that fancy stainless plumbing, you can buy a set of spare gauges. And an IR temperature gun...

 

[rob.mwpropane]

Measure temp. Temp will tell you more than pressure will.

I doubt it makes sense financially.

You aren't going to be plugging in high-dollar precision gauges. The gauges are just there to tell you "yup, this is in a reasonable pressure range".

As such, for the price of all that fancy stainless plumbing, you can buy a set of spare gauges. And an IR temperature gun...

Temp is also another tool, but there is a chart in the Rix manual that specically states what the 2nd stage pressure is in spec when the 3rd stage pressure is wherever it is. It also dictates what it means if it's out of spec.

I don't know enough about other compressors to comment on pressures, but I would assume they would have something similar. Personally I monitor both, both are good tools to have. Pressure on 2nd and 3rd and temp of the heads with an ir gun.

 

[-JD-]

Well, If I go to a remote panel (likely removable) system, I still think this has some validity. But I agree, it may be adding complexity to avoid damage risk (to gauges) that can be reasonably mitigated by careful location planning and selection, and it is certainly adding significant cost.

Also, you guys got me thinking about shifting the (saved) financial resources over to temperature monitoring: Thermocouples clamped on gas tubing for reasonable-cost, continuous temperature monitoring of stage outlet temps?

 

[Cio]

Well, If I go to a remote panel (likely removable) system, I still think this has some validity. But I agree, it may be adding complexity to avoid damage risk (to gauges) that can be reasonably mitigated by careful location planning and selection, and it is certainly adding significant cost.

Also, you guys got me thinking about shifting the (saved) financial resources over to temperature monitoring: Thermocouples clamped on gas tubing for reasonable-cost, continuous temperature monitoring of stage outlet temps?

Temp and pressure are related, measuring temp will not require the modification of anything to monitor. Temperature is a much better indicator of system health than pressure is. If you want to do both, go for it, no harm there, but if you were to choose one and want a simple solution, it should be temp.

 

[Cio]

Temp is also another tool, but there is a chart in the Rix manual that specically states what the 2nd stage pressure is in spec when the 3rd stage pressure is wherever it is. It also dictates what it means if it's out of spec.

I don't know enough about other compressors to comment on pressures, but I would assume they would have something similar. Personally I monitor both, both are good tools to have. Pressure on 2nd and 3rd and temp of the heads with an ir gun.

IR on the heads isn't good spot to measure. I've never seen a temp sensor on a compressor head. IR the coolers, inlet and outlet, that will tell you everything.

 

[-JD-]

Temp and pressure are related, measuring temp will not require the modification of anything to monitor. Temperature is a much better indicator of system health than pressure is. If you want to do both, go for it, no harm there, but if you were to choose one and want a simple solution, it should be temp.

Honestly, without the push, I probably would not be monitoring temp, but I now hope/think it can be done simply and inexpensively (if not super-precisely) .

Pressure is useful for monitoring for head-valve leakage, PMV/BPR/Check operation, etc. Worth the investment to me.

 

[rob.mwpropane]

Temp and pressure are related, measuring temp will not require the modification of anything to monitor. Temperature is a much better indicator of system health than pressure is. If you want to do both, go for it, no harm there, but if you were to choose one and want a simple solution, it should be temp.

Again, the only compressor I have any experience with is a Rix SA-6, which is exactly what @-JD- is working on. Based on what the manual says, the best form of action would be to monitor 2nd stage pressure. (again... only a Rix, I don't know about others).

I am not the brightest crayon in the box, I'm sure there are plenty of ways to monitor the health of a compressor. I just know what Rix says is it's 1st line of defense for doing so. Pressure has to be out of spec in order for temp to rise (or you're pumping a gas other than air but that's entirely different conversation).

@Cio please have a read of this and tell me what you think?I honestly have only played around with an ir gun to see what was hot, but I do have interstate gauges on both 2nd and 3rd and they work awesome.