|
Expansion Tank size for Secondary closed loop
|
|
Source：Internet Author：Unknow Pubdate：2010-06-17
|
|
russgs (Mechanical)
27 May 10 12:58
Hi,
Can anyone explain what value to use for the maximum pressure, when sizing an expansion tank. This is on a closed secondary loop. If it were the primary side it would be determined by the boiler PRV, but what is the determining factor for a secondary loop with a water to glycol heat exchanger?
Thanks in advance for any help.
ChrisConley (Mechanical)
27 May 10 15:12
Maximum pressure would be system fill plus the discharge pressure of the circulating pump in the closed loop. Of course the entire loop won't be at the discharge pressure of the pump, so you've got some safety built in to that number.
walkes (Mechanical)
1 Jun 10 12:26
I would think the maximum pressure would be the relief valve setting for your pressure vessel on the secondary side (heat exchanger), less the static height of the system if the vessel is at the bottom. 字串1
Say your vessel or piping/fittings are designed for 125 psi and at the bottom, if the top is at 125 psi then the pressure at the bottom will exceed the design.
introengineer (Mechanical)
7 Jun 10 20:44
Hello Everyone,
Im new to the forum. Here is my problem. I suppose it is similar to the initial problem posed in this forum. I have a closed loop system with 30% acqueous prop. gylcol. The expansion tank is located near the pump inlet (about 22 feet of 4" NPS PVC pipe seperate the pump inlet and the tank). According to the P&ID and the Isometric there is no PRV or PSV anywhere on the system. Does anyone know how to calculate the fill pressure?
Some more input that may be necessary is there is no elevation change greater than 20 feet in the system. My initial guess at solving for the fill pressure is to take the pump discharge pressure and subtract the losses (piping valves etc.) up until the expansion tank as well as adding in the static head from the highest point in the system to the location of the expansion tank. Does anyone know if this is correct? Thanks so much for the help.
字串4
walkes (Mechanical)
17 Jun 10 8:51
Static head difference between the fill point and the highest point in the system (converted to psi) plus 5 psi to push air out. Pre-charged expansion tank may be around 12 psig. So a minimum fill pressure of 12 psi.
（Click：）
|
| Previous：Question about Sizing HVAC split Next：Thermal Insulation and Duct Liner |
|
[ Add TO Favorites]
[TOP] [PRINT]
[CLOCE WINDOWS] |
|
|
|
