Chilled water expnsion tank commissioning. 5

[commissioningtech]

Hi Guys,

Recently I have had to commission some chilled water systems but can't find any information on setting up the expansion tanks. By the time I get to site any manufacturers data is well and truely lost and as is the trend these days I am under pressure to get the job done instantly which doesn't allow time to chase data from uninterested manufacturers.

I believe I need make up supply pressure, tank pressure, system pressure and relief valve pressure but how do I apply this information?

Any help much appreciated, Mark.

 

[Vellum]

What type of expansion tanks are you setting up?

 

[Yorkman]

The term expansion tank can describe several type of systems the original type of expansion tanks were open to atmosphere, and the tank was located at the highest point in the system. If this is a closed system, it is probably a compression tank. If the compression tank is of the rubber diaphram type, which is on an air elimination type system: there isn't much to it, make sure that the air seperator is pipe correctly and it has an automatic type air vent mounted and functioning generally located on the top of the air seperator. The connection pipe from the system to the tank needs to be open. This tank is usually precharged to 15 psig using a shraider valve connection. If this is an air control system (the compression tank does not have a diaphram) there is usually a gage glass mounted on the tank. This procedure is a little more involved. As the system is filled the tank fitting vent is opened until you get water coming out of the coin/tank vent then closed as the system continues to fill. This internal line should have been cut so that the vent line length is about 1/2 the diameter of the tank. This keeps the water level low enough for the expansion of the liquid as it heats.The top of the system needs to be vented as you fill, the filling should continue until the system is vented and the top of the system is at about +5 psig cold fill pressure. If the tank is too small there will be a rapid rise/build up of system pressure as the temperature climbs. A 5-8 psig rise is quite normal.

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[lilliput1]

The engineer for the project should give you the following:

1. Expansion tank fill pressure (this should also equal the makeup water PRV setting).

2. System relief valve setting.

The expansion tank fill pressure should equal the static head of water on the expansion tank equal to the highest piping plus about 6'.

The relief valve setting should be the pressure at the relief valve location such that no portion of the piping see about 125 psig when the chillers are off and the water in the piping is at its max temperature.

 

[commissioningtech]

Thanks so much for your time guys,

I believe the tank to be the compression type. It has the shrader on top and a gauge at the inlet regulating valve.

The gauge reads around 1.8 bar and is nominated at 2.0 bar and has a relief valve nominated at 2.0 bar.

Standing head measured at around 160kpa at about 1 foot above inlet valve gauge location but was measured with a different gauge so given possible gauge inaccuracies I guess the 1.8 bar at the tank inlet valve sounds about right.

I had no points to read mains inlet pressure nor read shrader valve pressure.

I will in future obtain required data from the project engineer but should I be concerned about making any further measurements or adjustments to this particular job???

Thanks again for your help, Mark.

 

[commissioningtech]

Sorry guys,

The relief valve is nominated (labeled) 2.5 bar not 2.0!

Mark.