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Medical Gas Supply System
2.6
Installation Check.
2.6.1
Ensure that all pigtails are connected to the
cylinders and manifolds on both sides and that the
restraint chains are secure around the cylinders.
2.6.2
Isolate the device from the pipeline using the
main isolation valve (shown in Item 3, Figure 15).
2.6.3
Ensure that both bank isolation valves (Figure
15, Item 1 and 2) are fully open.
2.6.4
Use 1 cylinder per bank, slowly pressurise the
manifold (see Section 4.10 - Cylinder operation). Both
cylinder gauges (Item 17, Figure 1) should indicate full
cylinder pressure. The line pressure gauge (Item 11
Figure 1) should read typically as per Table 5, Section
4, adjust as necessary (see Section 4.5).
CAUTION! If used as a backup manifold it would
be recommended to set the line pressure at least 0.02
MPa below the main supply source pressure at full
design flow, to ensure the manifold does not supply
the pipeline during normal primary source operation.
2.6.5
Check for leaks, typically by listening for gas
escaping or leak detection fluid on joints.
2.6.6
Now ensure all bank cylinder valves are closed
ready for pressure drop leak test.
Figure 15 - Leak Test Valve Configuration.
1
2
No.
Description
1
Line Isolation Valve
2
Intermediate Isolation Valve (Three Way)
3
Line source Isolation Valve
Pressure drop leak test validation notes:
•
The Manifold Changeover System uses medical
regulators approved to EN ISO 10524-2 standard.
These standards have a maximum allowable
leakage across the regulator seat (internal) and to
atmosphere (external) as follows:
1
stage regulator, Internal
st
1
stage regulator, external
st
2
stage regulator, Internal
nd
2
stage regulator, external
nd
•
Therefore, the maximum pressure increase or
decrease witnessed at the line pressure will be
based on 2 regulators, 0.4 ml/min. The maximum
pressure drop witnessed at the cylinder pressure
will be based on the internal and external leakage
from the 1
ml/min.
•
Pressure drop tests are more commonly used on site,
as leaks can be difficult to measure. The equivalent
water capacity volume under test is used to calculate
the pressure drop from an allowable leakage rate.
•
From using the manifold water capacity the allowable
pressure drop or increase based on a leakage of 0.4
ml/min can be calculated as 0.00016 MPa/min, or
0.0096 MPa/hr witnessed at the line pressure. The
pressure drop witnessed at the cylinder pressure
from a 0.7 ml/min leakage would be as follows
depending on the number of cylinder connections.
3
No. Cyl.
MPa/Hr
No. Cyl.
MPa/Hr
1
•
Although the medical regulator allowable leakage is
only small, the effects can be witnessed within a few
hours due to the manifold having a small volume.
2
To put into perspective how small 0.4 ml/min is, if
applied to one J-size cylinder it would take nearly 12
weeks for it to drop by 0.1 MPa.
2.6.7
Monitor the pressure drop and assess as per the
above notes. Length of time for the test will depend on
the accuracy of the gauges used to be able to detect the
pressure drop.
21
and 2
stage regulator on that bank, 0.7
st
nd
1
2
3
1.78
1.09
0.78
60
70
80
4.2
3.7
3.3
0.1 ml/min
0.2 ml/min
0.2 ml/min
0.2 ml/min
4
5
0.61
0.5
90
100
2.9
2.6
4109992459.00
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