Getting serious about vacuum unit

Jim_from_Worcester

I'm starting a new thread because I'm getting serious about restoring the vacuum unit in my building. The vacuum pump can produce a vacuum when isolated but cannot hold it with the pumps off. Replacing all the seals, facings and seats that could affect the evacuated  chamber is an expensive proposition, and doing it incrementally from most to least likely culprit will take forever (there is a long lead time for these parts). It makes me wish I'd started this in June.





I cannot achieve a vacuum at all with inlet valve open to the system. It seems to me that testing the system piping for leaks will take a lot of time, so this is where I should start, instead of spending all the money up front on the unit itself. So my main question is whether the following sounds like a good approach?





1. Do my calculations and confirm the unit is sized correctly to begin with

2. Shut off all riser valves at the main and see If I can produce a vacuum; find and repair leaks if I cannot (I'm not sure of the best method method but am inclined to charge the system without the pumps running and use a mirror to detect steam)

3. Open each riser valve on by one and repeat the process used for the main. Most likely candidates would seem to be valve stem packing?

4. At the point a vacuum can be maintained in the system, replace all necessary seats, facings and seals that would prevent the vacuum from being held with pumps off.



My other question is whether number four should really be number two.



Thanks again,



Jim from Worcester

Jean-David Beyer

Finding leaks.

I am not a professional, but perhaps you could find leaks with a tiny air compressor (one with a regulator so you do not overpressure your system) to pressurize the system and then listening for the leaks with a stethoscope (possibly electronic). This might work faster than drawing a vacuum and waiting for pressure to go down.

nicholas bonham-carter

vacuum cleaning

can you first just make the system function as an atmospheric system, and look for and correct any leaks, then reactivate the vacuum features?

it will take a big air compressor to charge the system enough to show any leaks. why bother with that when you have an excellent pressurisation device already--the boiler!

i would think that these vacuum pumps must have taken quite a while to produce a vacuum from a cold start, whereas after steaming, there will be a vacuum naturally forming, which only has to be maintained by the pump.--nbc

Jim_from_Worcester

Vacuum System

Thanks guys,

I will do calcs first and see how long it should take to evacuate bases on cfm.



Yeah, I think using the boiler as compressor is the way to go.



I'll let you know how I make out.



Jim