Johnson Controls YORK YVAM 0350, Operation & Maintenance Manual

Page: 125 / 162

Conducting the gas pressure hold test
1. To monitor the system pressure over time, install a high-quality, high-resolution analog
pressure gauge on one of the shells. Use a pressure gauge that has a resolution of 2 psi
increments with a dial face at 3 in. in diameter or greater.
2. Before proceeding, make sure that the unit is at the initial evacuation level of 5 mmHg.
Important: To prevent freezing of any moisture that might be in the system, do not go
below 5 mmHg. See System evacuation for more details.
3. With the system in a vacuum, slowly charge nitrogen vapor only into the system.
4. Slowly build up the system pressure with dry nitrogen to the design working pressure (DWP)
as found on the chiller vessel data plates.
5. Allow the pressure to remain in the chiller based on Figure 51. This chart provides the hold
times for pressure hold testing based on the vessel diameter and length.
What to do next:
• For a unit with no loss of pressure, proceed to unit evacuation.
• For units where a leak is suspected and there is any amount of drop in recorded pressure,
proceed to either of the following leak detection methods: Conducting the soap visual gas
leak test or Conducting the optional trace gas leak test .
125 YVAM Control Center