Testing used panels for viabilty

[Really?]

Is there any advantage in using water @ 100psi over air @ 100psi , in testing old used panels for viabily? Should any other test be applied? Any flat thermal panel dealers in New Mexico?

[J.P.M.]

First and foremost, pressure testing needs concerns for safety.

Next: and while still on safety: Why 100 P.S.I. ? Know the original design pressure before you assume anything.
Next: do the collectors carry an OG-100 cert. program or similar cert. ?
Next: what does the nameplate (if any) data show ?
Checking for known solar thermal panel testing procedures might be something to consider.

Pneumatic testing (that is using air or other compressible fluid) test methods are, in theory at least, less involved until safety is considered then they get quite complicated very fast. This is because there can be and is much more potential for serious damage or injury in the pneumatic testing process. Reason: If, for example, a solar thermal collector that uses a non compressible liquid (such as water) as the working fluid is pressurized with a compressible fluid such as air, and it fails (that is, any part of the pressure boundary ruptures), there is some non small likelihood it will fail catastrophically, resulting in property damage or personal injury.

Hydrostatic testing (that is using a non compressible fluid such as water as the test fluid) often involves a bit more work to set up and provisions need to be made for test fluid availability and removal, but if the unit being tested springs a leak, it will, in all likelihood only mean something gets wet. Safety, while no less important, is much easier to design for w/hydrostatic testing.

See the A.S.M.E. Boiler and Pressure Vessel code for differences in testing requirements with respect safety concerns for pressure testing vessels or pressure boundaries with air vs. water. Most of the substantial extra requirements for pneumatic testing are all about safety.

Most of the extra requirements for pneumatic testing, which can be substantial, are due mostly to safety concerns if a failure occurs. Manufacturers of standard cookie cutter type A.S.M.E. coded pressure vessels such as residential water heater tanks and the like often take the time and make the somewhat substantial effort to set up pneumatic test areas and procedures required for code compliance with respect to test procedures. The test fluid handling is a lot easier and cheaper, and the added cost of the (believe me) extra precautions required is spread over many units, making pneumatic testing a more practical option..

It's all about safety. For small numbers of units to be tested, use water and spend extra time making sure the units are dry by air blowing after test. For the smart money, the lower cost and hassle of using air doesn't offset the consequences of a pneumatic testing failure.

As for dealers in NM, contact the NM Solar Energy association. See the net of details.

[Mike90250]

Difference being between Air and Hydro pressure testing, is air, compressed, continues to retain pressure and eventually (in a quarter of a second) grenade the test article. Think of the tire cages used for inflating large tires, to contain the rubber shrapnel if the tire explodes.
Conversely, hydrostatic testing, as soon as the leak happens, the pressure has "gone" and there is no further result, unlike a shaken bottle of carbonated beverage.

[J.P.M.]

Difference being between Air and Hydro pressure testing, is air, compressed, continues to retain pressure and eventually (in a quarter of a second) grenade the test article. Think of the tire cages used for inflating large tires, to contain the rubber shrapnel if the tire explodes.
Conversely, hydrostatic testing, as soon as the leak happens, the pressure has "gone" and there is no further result, unlike a shaken bottle of carbonated beverage.

For more info see: Engineering.com and search for "Pneumatic Testing of Pipelines as an Alternative to Hydrostatic Testing" from 07/31/2014. A decent practical article with some tech. discussion of why pneumatic testing may not be for the faint of heart or foolish.

[LucMan]

50 psi of air should be all you need. Soap all your temporary connections to check for leaks and if the pressure holds for 1/2 hr you should be good to go.

[J.P.M.]

50 psi of air should be all you need. Soap all your temporary connections to check for leaks and if the pressure holds for 1/2 hr you should be good to go.

For reasons previously discussed, and particularly with used equipment with perhaps unknown history, based on my training and experience as a mechanical engineer, a good part of which was spent designing pressure vessels and piping systems, I believe this is an unsafe recommendation.

If the only concern is about leaks, pressurize to 1 or 2 PSI and then soap bubble test and repeat under the same 1 - 2 PSI an hr. later to check for leaks. For proof testing for vessel integrity under a working pressure greater than, say 15 PSI(G) or so, pneumatic testing can result in damage or personal injury in the event of failure.

If I knew someone was testing a used pressure vessel of unknown origin and/or service history pneumatically at some substantial pressure (usually > 15PSI(G)), I'd follow the pressure vessel designer's rule of thumb and be no closer than one zip code away from the test site.

[Really?]

Thank you all for all the kind replies. This site is extremely helpful.