Gascon Manifold Maintenance instruction
GASCON SYSTEMS
AUTO CHANGE-OVER
MANIFOLD MAINTENANCE
INSTRUCTIONS
GASCON SYSTEMS AUTO CHANGE-OVER AUGUST 2003 PAGE 1 of 11
MANIFOLD MAINTENANCE INSTRUCTIONS ISSUE 1
INDEX
Page
1.0 INTRODUCTION 2
2.0 IDENTIFYING THE MANIFOLD 3
3.0 TEST A - TEST GAS FAILURE ALARM SYSTEM 4
4.0 TEST B – TEST FUNCTION OF CHANGE-OVER MECHANISM 5
5.0 TEST C – TEST MANIFOLD PRESSURE SETTINGS 6
6.0 TEST D – TEST PRESSURE RELIEF VALVES 7
7.0 TEST E – PRESSURE CONTROL ASSEMBLY SERVICE 7
8.0 TEST F – INSPECT FOR EXTERNAL LEAKS 7
9.0 TEST G – INSPECTION OF CYLINDER LEADS 8
10.0 TEST H – CHECK THAT THE CYLINDERS HAVE BEEN CHANGED 8
11.0 TEST I – CHECK FOR EXCESSIVE FROSTING/CONDENSATION 8
12.0 TEST J – TEST HEADER NON-RETURN VALVE FUNCTION 9
13.0 TEST K – TEST OF FLASHBACK ARRESTORS 9
14.0 TEST L – INSPECT FOR UNAUTHORISED MODIFICATIONS 9
15.0 PRESSURING & RE-PRESSURISING PIPELINE SYSTEMS 9
16.0 MAINTENANCE SCHEDULE – MEDICAL & CRITICAL PROCESSES 10
17.0 MAINTENANCE SCHEDULE – NON-CRITICAL PROCESSES 11
1.0 INTRODUCTION
These maintenance schedules are applicable for the following Gascon Systems auto change-over manifolds:
M120, PM120, HM120, MM120, M200TT, M500, MM500, MM500TT, M700, MM700, M1000 & MM1000.
There are two recommended maintenance schedules, one for medical and other critical process applications
and another for non-critical process applications. A critical process application is considered to be a process
when any interruption to pipeline system in undesirable. A non-critical process application is considered to be
a process where a short interruption to the pipeline system is acceptable.
Other documents relating to auto change-over manifolds that designers, installers and users of manifold
systems should be familiar with are:
AS2896 – Medical Gas Systems
AS4289 – Oxygen and Acetylene Gas Reticulation Systems
Gascon Systems Manifold Installation Instructions
Gascon Systems Manifold Servicing Instructions (authorized repairs only)
These instructions include descriptions of the recommended maintenance tasks, as well as procedures for
carrying out these tasks. The two maintenance schedules at the end of these instructions show the
recommended frequency for the maintenance tasks.
It is recommended for organisations that have an auto change-over manifold/pipeline system installations
should keep log book records about the system. Information that should be included in these records are;
system design information, drawings, commissioning hand-over paperwork, maintenance/servicing schedules
and service history.
(Installation and testing of non-flammable medical gas pipeline systems),
GASCON SYSTEMS AUTO CHANGE-OVER AUGUST 2003 PAGE 2 of 11
MANIFOLD MAINTENANCE INSTRUCTIONS ISSUE 1
2.0 IDENTIFYING THE MANIFOLD
Every Gascon Systems manifold has a label affixed to the
underside of the first stage regulator body. This label
includes a brief part number description and the individual
serial number of the manifold, (refer diaphragm).
When discussing any issues about a particular manifold,
always quote this serial number so Gascon Systems can
refer to their internal records on the manifold.
Each manifold comes with an individual specification sheet. The information contained on this sheet is
important when undertaking any maintenance of the manifold. The information on the specification sheet
includes the following:
- Manifold model,
- Date of manufacture,
- Manifold serial number,
- Maximum working pressure,
in-use
- Manifold first stage “
- Manifold outlet pressure setting,
- First stage pressure relief valve setting,
- Recommended service kit part number.
The diagram below shows how the “
position. The diagram also points out a few items referred to in this document.
” and “
in-use
reserve
” and “
” pressure settings,
reserve
” cylinder banks alternate according to the lever
M120-600-OXY
S/N 020125
GASCON SYSTEMS AUTO CHANGE-OVER AUGUST 2003 PAGE 3 of 11
MANIFOLD MAINTENANCE INSTRUCTIONS ISSUE 1
3.0 TEST A - TEST GAS FAILURE ALARM SYSTEM
Any alarm systems connected to a manifold should be tested to ensure that they are operating correctly. To
check for the correct operation of the alarm system, refer to the alarm system manufacturers instructions.
The signals to alarm systems are usually generated from pressure switches. These pressure switches need to
drifted
be tested to ensure that their set point has not “
3.1 Change-over Pressure Switches
There are two methods of using pressure switches to indicate the change-over of cylinder banks. Using a two
pressure switch system, (one on each cylinder bank inlet to the manifold), or using a one pressure switch
system, (a pressure switch located at an intermediate point between the first and second stage manifold
regulators). Pressure switches may operate in Normally Open or Normally Closed modes, but Normally Open
is more commonly used in medical and critical process applications.
3.1.1 One Switch Systems
The one pressure switch system works on the pressure differential between the first stage regulator “
and “
reserve
” pressure settings. This is the more commonly used method for detecting the change-over of
cylinder banks. The more commonly used pressure settings are listed below.
“
RESERVE
PRESSURE
SETTING
750 kPa 1000 kPa 850 kPa 900 kPa 50 kPa
800 kPa 1100 kPa 920 kPa 980 kPa 60 kPa
1000 kPa 1250 kPa 1125 kPa 1175 kPa 50 kPa
2000 kPa 2700 kPa 2300 kPa 2500 kPa 140 kPa
”
“
IN-USE
PRESSURE
SETTING
”
P/SWITCH SET POINT
ON FALLING
The procedure for testing whether a one change-over pressure switch system is functioning correctly is the
same as that detailed in Test B (test function of manifold change-over mechanism). To check at what
pressure the switch is activated, a test gauge must be fitted to the manifold test point. On medical and critical
process application manifolds this can be done without interrupting the manifold operation by using the
isolation valve on the test point. On non-critical applications the flow to the pipeline may require to be
interrupted while fitting the test gauge. Monitor pressure on the test gauge as the manifold nears the changeover point. The pressure switch should activate at the specified set point. When re-opening the cylinder
valves, very slowly open the first valve and monitor at what pressure the switch is re-activated (reset)
3.1.2 Two Switch Systems
The two pressure switch system uses two pressure switches, or contact gauges, connected directly to the
cylinder contents side of each cylinder bank. These directly measure the cylinder pressure and are nominally
set to operate at 1.5 times the “
reserve
set point, and the deadband of the pressure switch are less critical on a two switch system than that for a one
switch system. The more commonly used pressure settings are listed below
” pressure setting specification of the manifold. The accuracy of the
“
RESERVE
PRESSURE SETTING
230 kPa 350 kPa
750 kPa 1130 kPa
1000 kPa 1500 kPa
2000 kPa 3000 kPa
”
” from their original settings.
MAXIMUM P/SWITCH
RESET ON INCREASING
PRESSURE
CHANGE-OVER
P/SWITCH SETTINGS
PRESSURE
in-use
MAXIMUM
P/SWITCH
DEADBAND
”
GASCON SYSTEMS AUTO CHANGE-OVER AUGUST 2003 PAGE 4 of 11
MANIFOLD MAINTENANCE INSTRUCTIONS ISSUE 1
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