Attachment_3_-_Expansion_Tank_Service_Diagram.pdf
PDF 533 KB Posted
- Attached to
- Inspection and Repair of HVAC at Heritage Center
- Solicitation number
- 140P1423R0004
About this file
This document provides instructions for pre-charging an expansion tank air bladder and details for a federal contract opportunity for inspection and repair of an HVAC system. The expansion tank service diagram outlines the procedure for isolating the tank from the system, draining water pressure, and filling the air side of the tank to the desired system water pressure using an air compressor and gauge. The related federal contract opportunity is a solicitation issued by the National Park Service Intermountain Region, within the Department of the Interior. The solicitation seeks inspection and repair services for the HVAC system at the Heritage Center in Yellowstone National Park.
View the file
Other files
Show all 11
On GovTribe
Work with this file
- Download the original file
- Contacts named in this file
- Similar government files
- Ask GovTribe AI about this file
Text version
Pre-Charging the Air Bladder on an Expansion Tank
Expansion tanks come pre-charged with 12 psig, which is an adequate charge for a 2-story building. The pressure in an expansion tank needs to be set according to the static fill pressure of the system for each job.
Examples:
1. If the elevation from the expansion tank to the highest point in the building is 20 feet (2-story building), the precharge is 0.433 psi/ft * 20 feet = 8.66 + 4 psi psi = 12.7 psi
Note – This is not a “precise” number.
For a 2-story building, typically round this number down to 12 psi.
2. If the elevation from the expansion tank to the highest point in the building is 50 feet (5-story building), the precharge is 0.433 psi/ft * 50 feet = 21.6 + 4 psi psi = 25.7 psi
Again, this is not a “precise” number. Round the number as needed.
Tank Pre-Charge Procedure
1. Close the isolation valve to the system and Isolate the expansion tank XT-1 from the system
2. Open the drain valve to drain all the water pressure off the water side of the expansion tank.
Leave the drain valve open during air-side bladder pre-charge.
3. With an air compressor & air pressure test gauge, fill the air side of the expansion tank to the desired system water pressure at the air charging valve (Schrader air valve on top, similar to a tire fill valve)
4. Shut the drain valve
5. Open the isolation valve to the system
File details come from the government source that posted it. Updated .