Table of Contents
Advertisement
Medical Gas Supply System
2.6
Installation Check.
2.6.1
Ensure that all tailpipes 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 figure 15, item 3).
2.6.3
Ensure that both bank isolation valves (Figure
15, item 1 and 2) are fully open.
2.6.4
Ensure the test point isolation valve (figure 15,
item 4) is closed.
2.6.5
Use 1 cylinder per bank, slowly pressurise the
manifold (see section 4.10 - Cylinder operation). Both
cylinder gauges (figure 1, item 23) should indicate full
cylinder pressure. The line pressure gauge (figure 1, item
18) should read typically as per table 6, 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 0.2 bar
below the main supply source pressure at full design
flow, to ensure the manifold does not supply the pipeline
during normal primary source operation.
2.6.6
Check for leaks, typically by listening for gas
escaping or leak detection fluid on joints.
2.6.7
Now ensure all bank cylinder valves are closed
ready for pressure drop leak test.
Figure 15 - Leak Test Valve Configuration.
No.
Description
1
Line Isolation Valve
2
Intermediate Isolation Valve (Three Way)
3
Lockable Isolation Valve
4
Test Point Isolation Valve
Pressure drop leak test validation notes:
•
The Manifold Changeover System uses medical
regulators approved to BS EN ISO 10524-2 standard,
as required by ISO and HTM medical pipeline
standards. These standards have a maximum
allowable leakage across the regulator seat (internal)
and to atmosphere (external) as follows:
1
1
2
2
•
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 0.0016 bar/min, or 0.096
bar/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.
No. Cyl.
Bar/Hr
3
No. Cyl.
4
Bar/Hr
•
Although the medical regulator allowable leakage is
1
only small, the effects can be witnessed within a few
hours due to the manifold having a small volume.
To put into perspective how small 0.4 ml/min is, if
applied to one J-size cylinder it would take nearly 12
2
weeks for it to drop by 1 bar.
2.6.8
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.
2.6.9
and relieve the pressure from within the manifold, then
close test point isolation valve.
2.6.10 The installation must now be purged as per HTM
02-01 for UK installations, or as per relevant standards if
installed outside the UK.
17
stage regulator, Internal
st
stage regulator, external
st
stage regulator, Internal
nd
stage regulator, external
nd
and 2
stage regulator on that bank, 0.7
st
nd
1
2
1.78
1.09
6
7
0.42
0.37
Monitor the pressure drop and assess as per the
Open test point isolation valve (figure 1, item 15)
0.1 ml/min
0.2 ml/min
0.2 ml/min
0.2 ml/min
3
4
5
0.78
0.61
0.5
8
9
10
0.33
0.29
0.26
4109992485.00
Advertisement
Table of Contents
