How to Install, Calibrate, and Maintain a Manometer for a Spray Booth (Includes Video)
What is a Spray Booth Manometer and Why You Need One
A manometer is a visual gauge that allows the paint booth operator to have a visual way of confirming when their paint booth filters may need changed. In many areas it is a requirement and can result in an immediate fine. The gauge itself is very affordable and will save you from dealing with legal penalties. For it to be of benefit, it must be properly installed, which is what we will cover in this article.
Manometer Placement and Installation
A manometer will need to be placed on the side of your spray booth between the exhaust chamber and the painting area of the booth. The reason being that their will be two hoses that will come off the top of the manometer one will plug into the “high” side and the other into the “low” side. The high side hose will insert onto a bulkhead fitting that has to feed into the spray booth in front of your booth filters. The low side hose will insert onto a bulkhead fitting that has to insert into the booth behind the filter bank into your exhaust chamber. The bulkhead fittings will be included in your manometer package typically. In addition to the bulkhead fittings the manometer will have a level on it. Make sure to install the manometer level with the spray booth otherwise you may have inaccurate readings with your manometer gauge.
Once you have installed your manometer you will need to fill it with gauge oil. The trick to filling the manometer is to go slow and make sure you have the gauge adjustment knob fully backed out. Try not to ever overfill the gauge because then you may have trouble setting the gauge to a zero reading (will cover zero reading shortly). Once you have enough gauge oil it is time to calibrate the gauge. To calibrate the manometer set the gauge so that it reads zero without the booth on. You will then want to ensure the booth filters are new and turn on the spray booth (DO NOT USE OLD FILTERS REPLACE THEM). With the booth running the gauge should have increased (if not their is an issue with your installation). The new increased pressure difference the gauge is reading is the “clean benchmark” which you should mark with a green marker. This represents the pressure difference when your filters are brand new. From this mark you should move up the gauge about 0.4 Inches of water column (not physical inches) and establish a second mark which will be your dirty benchmark (or when your filters should be changed). Ultimately the visual gauge of the manometer is helpful but if your air in the paint booth seems to have overspray hanging it is usually better to go ahead and change your paint booth filters.
There are a few important things to do to keep your manometer operating well. First is to make sure that the bulkhead fittings remain open to the inside of the paint booth and exhaust chamber. If paint builds up on the bulkhead fittings you will not receive a correct reading from your manometer (this is easy to fix with a pick to remove the coating over the top of the bulkhead inside the booth). Second, you should reset the booth to zero when it is not running at least every couple weeks so that your manometer reading is not incorrect. Third, from time to time you will need to replace the gauge oil in your spray booth manometer as it will evaporate over time.
By following these tips and advice for a spray booth manometer you can install and maintain a well functioning manometer which will help with code compliance as well as knowing when to change your spray booth filters to maximize the life of your spray booth fan.
Photo by Sebog6 (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons