Fixing leaking steam traps

Andrew Rudin

I am working with a church in Westchester County, NY that needs to replace their thermostatic "cage units" in their steam traps.
The original housings are Warren-Webster. This is a low pressure system (1.5 to 2.0 psi).
They were disappointed with Barnes and Jones, first installed about 25 years ago. They also tried Tunstall capsules which
seem to last somewhat longer.

What recommendations do you have for the brand of replacement thermostats and how long do you think those might last?
Can you also recommend a good steam contractor who often works in Westchester County, NY ?

nicholas bonham-carter

Remember that any of these traps may fail if the pressure in the system rises above 1psi. The standard pressuretrol is not accurate enough for this job, and should be replaced with a vaporstat, (0-16 ounces).
There will not only be traps on the radiators, but also crossover traps to let the air out at the end of the mains. If the air cannot get out, then the steam cannot get in.--NBC

Sailah

I'm sorry you had a bad experience with Barnes & Jones, let's see if we can fix that. It would be helpful if you sent me some pictures of the Warren Websters, specifically a model number if possible as well as a picture of the inside showing the seat. Quite often the installers don't remove the seat which does not give a good seal. Ask be sure to not use pipe dope or Teflon tape on the covers as it can cause leaking traps.

We typically tell customers that regular cage units last 3-5 years. My parents have B&J C traps in their house that are 40+ years and still function, I know because I tested them. So the life can vary dramatically.

We also manufacture a "super trap" which uses a Monel bronze bellows, stainless cage, seat & plug as well as a stainless mesh screen. It addresses many of the shortcomings of the regular cage units which are built to a price point. I would need to know your trap model to see if we offer a super trap for it.

At the end of the day, traps are just one part of the system. If the other parts aren't being maintained, no magic trap is going to last forever.

I think between Tunstall and Barnes & Jones, you just named the only suppliers/manufacturers of cage units out there. We manufacture cage units for many OEMs so if it looks like one of ours, it is one of ours.

Sailah

nicholas bonham-carter said:

Remember that any of these traps may fail if the pressure in the system rises above 1psi.

Our regular radiator traps are rated from vac-25psig, our industrial cage units range from vac-65psig up to 300psig.

I know you were addressing a slightly different point, just wanted to make sure that if you put more than 1 psi on our traps you aren't going to fail them. I routinely test traps that customers send in at 15psig.

Incidentally every single complete trap that leaves our factory is tested under live steam by our steam guru Danny. He's been testing and working at Barnes & Jones for 39 years.

nicholas bonham-carter

You are right about the resilience of traps subjected to higher than 1 PSI pressure, and also that I was referring to other vapor system problems caused by higher than ideal pressure.
Now for an off topic question: in a subatmospheric system, operating at lower temperatures, than 212 degrees, where the traps still work. How can that be when your volatile fluid must still vaporize at the same temperature, as it is sealed, and still open and close at the different cooler temperatures in a vacuum?--NBC

Sailah

The traps will work identically from 25” Hg Vacuum to 250 PSIG saturated steam.  The reason for this is because when we fill the elements we draw 25 “ Hg vacuum on the inside of the element to pull it up to a solid stop before sealing the fill hole.  When steam surrounds it while in service then the fill on the inside of it flashes back to steam to create a “balance pressure” .  This process causes the element to expand  approximately .100” (+ or -) and that seals off the plug to the seat.

 

That is why most subatmospheric systems (VariVac)  use either Mepco or B&J elements.  The other manufacturers don’t do this so their elements will not work.

 

The B&J and Mepco element close based upon the Saturated Steam principles.  Steam is steam to both elements whether it is steam at 190 degrees at 10” Hg vacuum or  230 degrees F at 5 psig.