Pressure Testing Large Jobs
Matthew Taylor gives a short presentation and performs a demonstration about nitrogen pressure testing for large jobs (commercial HVAC and refrigeration). Pressure testing with nitrogen will help you ensure that there are no leaks in systems with up to several hundred feet of tubing.
Nitrogen is ideal for pressure testing because it's inexpensive, and its pressure doesn't respond significantly to changes in temperature. You can easily fill the entire system with nitrogen and determine if you have leaks in places you can't reach with a leak detector. You do NOT want to pressure-test a live system with refrigerant in it; you'll have to isolate the part you want to pressure-test.
Before pressure testing, think through your application; you'll want to know if you have a new store, a new line set, new cases, or an active rack. Each one will require a unique approach. When starting the test, you'll want to make sure you have a gauge that you can leave attached to the system for a long time, sometimes upwards of 30 days for new systems; analog gauges are sometimes preferable for that reason, and they don't need to be perfectly calibrated as long as you can see that the pressure is maintained. The original pressure should be documented so that you will know how much the system has leaked when you return to it.
When you pressurize the system, set the nitrogen regulator to the maximum test pressure as recommended by the manufacturer and apply a leak reactant (bubble solution) to the joints to check for bubbles and microfoam, both of which indicate leaks. When you've finished the test, you can release the nitrogen and either address the leaks and redo the pressure test or proceed with evacuation.
Buy your virtual tickets or learn more about the 4th Annual HVACR Training Symposium at hvacrschool.com/symposium.
Read all the tech tips, take the quizzes, and find our handy calculators at www.hvacrschool.com/.
Пікірлер: 8
Pump, pump, pump it up 🎶 👌. Thanks for another great video!
On the temperature compensation thing, what matters is the temperature of the nitrogen, not the temperature of the ambient air so if the tanks are sitting on a roof or in a boiler room or even in the back of the truck it can throw you for a loop. It’s worth waiting an hour for temperatures to settle to ambient
Matthew is the man! Great video
A few things he may have forgot to mention #1 when using an analog gauge ( Spring gauge) that pressure test should be between 25 and 75% of that spring gauge’s range #2 temperature is not the only thing that affects the escalation or de-escalation of the pressure test , Direct sunlight could have a big effect as well (A 90° day with the sun under the clouds and a 90° day with the sun beating down on your piping,I can assure your pressures will be different ). #3 pressure testing piping where half of it is inside and half of it is outside can mess with you (I try to note: the inside and outside temperatures , in winter time inside unit heaters can really mess with you ). #4 installing an isolation valve at the inlet of your gauge can give you a little peace of mind, turn it off, and that gauge should stay put , if you see a drop there’s something wrong with that gauge or gauge connection. Pressure testing is kind of like driving a car , once you have the experience of driving it in most weather conditions , you got it🏁👍.
I always give gauges a little tap before taking a reading. Not uncommon for them to be a little sticky.
maybe 2-3 lbs at 50 psi but test a system up to 600 psi and that 90 to 70 degrees will be significantly more. Closer to 23psi pressure difference.
The Big Blue bubbles up when pulling a vaccuum? That , Sir, makes no sense. You have to have a positive pressure to make soap bubble
Seems like that's out of order. Why is he telling us to do a bubble leak check AFTER letting the system sit on pressure for "2 weeks" or "a month"? Let's find the leak before we waste that amount of time