Multi-DENCO Medium Connections
FläktGroup DC-2013-0101-GB • Subject to modifications • R5-08/2020 73
6.3.1 For model sizes 010 to 065
These instructions apply to all version with a direct expansion circuit.
For standard units, all devices fitted to the low pressure side of the system are sufficiently
pressure rated and can remain connected to the system during pressure testing.
1: Ensure that the adjacent area is clear of non-essential staff, complete a risk
assessment and establish an exclusion zone for safety purposes.
2: Insert 3.5 bar nitrogen into the unit to identify first fix leaks, if leaks occur, release
the nitrogen, repair the issues and re-insert nitrogen to 3.5 bar.
3: Complete a strength test by pressurising system with dry nitrogen to 47.6 bar and
leave on test for a minimum of 15 minutes.
4: To ensure quality of installation, it is highly recommended to conduct a "Tightness
Test". Reduce the pressure in the system to the Maximum Allowable Pressure
(MAP) and observe for 24 hours (recommended). If site conditions do not permit,
then the test should be conducted for a minimum of 6 hours for the "Tightness Test".
5: If successful, reduce the pressure down to zero by using the relief valve on the
nitrogen regulator or charging manifold.
6: Repair any leaks found and then repeat steps.
7: If the client or end-user requires witnessing the pressure test, carry out this witness
at this point making notes of dates, times and pressures.
8: At the completion of the pressure test, the Oxygen-Free Nitrogen charge should be
safely purged away leaving a holding charge prior to the evacuation process.
Ensure you have recorded the holding charge in your records at this point.
9: On completion, prepare and sign the 'Pressure Test Certificate' (chapter 13.2).
6.3.2 For model sizes 092 and 130
These instructions apply to all version with a direct expansion circuit.
1: Ensure that the adjacent area is clear of non-essential staff, complete a risk
assessment and establish an exclusion zone for safety purposes.
2: Low side strength test; Complete a strength test on the whole system by
pressurising with dry nitrogen to a maximum of 33.0 bar and leave on test for a
minimum of 15 minutes.
3: High side strength test; On completion of step 2, ensure that the low pressure side
remains isolated and at 33.0 bar, then increase the dry nitrogen pressure to
47.6 bar on the high side and then leave on test for a minimum of 15 minutes.
NOTICE
During the pressure test, system pressures exceed the maximum values specified
by the supplier. Exceeding these pressures could damage the sensors resulting
in incorrect operation by the unit.
• Ensure low pressure switches are disconnected before pressure testing.
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