NA7.5.7 Valve Leakage Acceptance

Use Form NRCA-MCH-08-A

Purpose of the Test

The purpose of this test is to ensure that control valves serving variable flow systems are designed to withstand the pump pressure over the full range of operation. Valves with insufficient actuators will lift under certain conditions causing water to leak trough and loss of control. This test applies to the variable flow systems covered by §140.4(k)1 Chilled and hot-water variable flow systems, §140.4(k)2 chiller isolation valves, §140.4(k)3 boiler isolation valves, and §140.4(k)5 water-cooled air conditioner and hydronic heat pump systems.

Related acceptance tests for these systems include the following:

•      NA7.5.9 Hydronic System Variable Flow Controls Acceptance

Testing time will be greatly reduced if these acceptance tests are done simultaneously.

Instrumentation

Performance of this test will require measuring differential pressure across pumps. The instrumentation needed to perform the task may include, but is not limited to:

•      Differential pressure gauge or

•      Handheld hydronic manometer

For accurate comparison with the pump curves it is important that you use the taps on the pump casing for these measurements. Taps on the inlet and discharge piping to the pumps will not correlate to the pump curves.

Test Conditions

The whole hydronic system must be complete – all coils, control valves, and pumps installed; all piping is pressure tested, flushed, cleaned, filled with water; BAS controls, if applicable.

All equipment start-up procedures are complete, per manufacturer’s recommendations.

Document the initial conditions before overrides or manipulation of the BAS.  All systems must be returned to normal at the end of the test.

Estimated Time to Complete

Construction inspection: 0.5 to 2 hours (depending on availability of construction documentation and complexity of the system.)

Functional testing: 30 minutes to 3 hours (depending on the complexity of the system and the number of valves)

Acceptance Criteria

Provisions have been made for variable flow:

System has no flow when all coils are closed and the pump is turned on.

Potential Issues and Cautions

The Acceptance Agent will likely need access to the EMCS during testing

Running a pump in a “deadhead” condition (no flow) for more than 5 minutes can damage the pump seals or motor. Care must be taken to set up the test so that the pump only needs to run for 5 minutes or less.

If balance valves are used for isolation of three-way valves or pumps, their initial position must be noted prior to using them for shut off of flow so that they can be returned to their initial position at the end of the test.