Makeshift Manometer for testing pressuretrol, vaporstat, gauges.

Timco

My customers would laugh me out of their homes if I put that to use, but it is interesting. I'll stick with my comb analyzer. Maybe if I was on 'surviver' and had to check the draft or be voted off...maybe bamboo shoots & coconut juice?

Tim

Captain Who

Makeshift Manometer for testing pressuretrols, vaporstat, gauges

Below is a picture of it if anyone is interested. It is crude but inexpensive to make and makes pressure measurements to a high degree of accuracy and resolution since it uses a water column of known density. Just run a clear vinyl hose up a stairway from floor (I used my basement stairs and floor) and measure the water column height with a tape measure. A valve at the bottom allows water column to be reduced slowly and controllably (I just used a clamp). Water can be added at top of tube with a small funnel and a watering can.

I was able to determine that my pressuretrol is functioning reliably and reasonably accurately after all. It is not cycling on my boiler, but I also now know that that is because my boiler is not reaching a high enough pressure to reach the cut out of the pressuretrol. The pressure gauge on my boiler was giving an erroneous reading of around 2.5 to 2.75 psi which should have been causing the pressuretrol to cycle (it is set to cut out at 1.5, cut in at 0.5), but I found out that the gauge is mounted by the factory to the boiler with a brass snubber which had a very tiny hole in it barely big enough to push a small pin through. It was clogged which caused the gauge to read too high and also it caused the gauge to return to zero verrrrry slowly after firing stopped.

The readings for the pressuretrol were:

Cut-in: 0.52 psi (+/- .05 psi)
Cut-out: 1.70 psi (+/- .10 psi)

The readings for the pressure gauge were:

Gauge read 3.0 psi when actual pressure was 2.30 psi
Gauge read 1.9 psi when actual pressure was 1.17 psi

Now my pressure gauge barely moves when my boiler fires. Maybe with this cold front coming though........

scrook_2

U-tube Dwyer

You could buy a roll up U-tube manometer from Dwyer instead, functionally the same (shorter though) and add a clear vinyl extension tube to it for higher pressure measurements, but you'd get no better results. Otherwise, clip the tube to a painted board w/ a yardstick on it and use a half round disk at the bottom to guide the tube at the U so it looks prettier -- good for fuel gas as well as residential steam measurements

BTW a couple drops of fluorescein dye (Dwyer sells this too I believe) makes the water easier to see in the tube.

Captain Who

More info. on manometers


Thanks, Damn... I should have known I didn't invent it - LOL. I looked into it and found the following link from Dwyer: http://www.dwyer-inst.com/htdocs/pressure/Series1221-1222-1223Intro.CFM

I think someone could buy a short economical one 1221-12-WM for $22.25 and modify it with the necessary adaptors on one leg to attach pressuretrol, vaporstat, pressure gauge or whatever to be tested or calibrated. Your idea of a board with a tape measure attached sounds good, along with the extension tubing to get enough pressure. However, to do what I did with the pressuretrol cut-in calibration you would have to add a release valve at the bottom of the U and I don't know if the bottom of the U is hard plastic or soft plastic that could be cut into to add a t-fitting and valve here. The valve is helpful for slowly releasing water from the atmospheric side of the U to find the cut-in point of the pressuretrol or vaporstat.

Of course a pro could simply bring a low pressure gauge which is known to be accurate and pipe it in next to the pressuretrol or vaporstat on the boiler, assuming it is producing enough pressure in operation. Mine wasn't at the time. I guess the manometer would be useful for calibrating and checking stuff off the job site and off the boiler so you know it is accurate and working properly.

Oh well, I'll go watch some Gilligan's Island reruns and drink some coconut milk.......

Dale

plastic hose

I have a boiler drain cap center tapped for a 1/8 hose barb, and 72 inches of coiled clear 1/8 tubing, I use a spring clip to the basement ceiling and measure the starting and final water distance in inches. Works fine to show steam pressure very accurately.

scrook_2

Magnehelic

Dwyer's Magnehelic gauges are rugged & nice for low pressure measurements -- just don't expose it *directly* to steam.

For P-trol setting you could pressurize the control's leg of the U-tube w/ a squeeze bulb, etc., to jack up the pressure to cut-in, then vent it till cut-out w/o a tee at the bottom.

Tough to beat a manometer, only one moving part (until you leave it in the truck overnight in winter -- then there's (temporarily) no moving parts!)