IM-P157-38
CMGT Issue 4
27
Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
Note:
Before actioning any maintenance programme observe the 'Safety information' in Section 1.
5.1 Importance of cleaning
Regular cleaning of the mixing valve and hose gun is required to prevent scale build-up and continued safe
operation. This is especially important if they are used in hard water areas. In the event of mixing valve failure
the TCO1 will operate and close at a temperature of 95
°C (203
°F). It is not re-settable and the mixing valve
must be inspected in order to discover the reason for the valve going over temperature, and serviced before
the temperature sensitive element in the TCO1 is replaced. If inspection of the mixing valve has not explained
the reason for the TCO1 failure, the rest of the mixing valve station and all supply pipework and attendant
pressures must be reviewed until the fault has been traced and rectified; please see Section 7, 'Fault finding'.
The hosedown station must not be used until any rectification work has been completed.
The element must
be replaced before recommencing operation of the hosedown station.
The spares pack (see Section 6) is the same for
½
" and
¾
" hosedown stations.
The hosedown station must always be operated with an element in the TCO1 to prevent steam
reaching the hose. In the event that the hosedown station is used without an element in the TCO1
then Spirax Sarco will not accept any consequential liability for the operation of the hosedown
station in this manner.
Following operation of the TCO1, the hose and hosedown gun should be inspected for any sign of wear or
damage. The hosedown station should form part of a regular maintenance programme, appropriate to the
operating conditions and environment.
5.2 Cleaning procedure
(To be carried out by suitably qualified persons only)
When carrying out cleaning of the valve consideration should be given to total valve refurbishment by fitting
a maintenance kit. Turn off and isolate the steam and water supplies, remove any residual pressure from the
system by operating the hose gun and remove the gun from the hose. If the gun is to be cleaned (Reassemble
the gun to the hose following Figures 9, 10 and 11, page 16). Undo the 3 union joints and remove the mixing
valve from its fixings and move it to a maintenance area. Before reassembly ensure all union joint gasket
faces are clean and ready to receive the new gaskets.
Referring to Figure 14. Remove the temperature adjustment knob (
12
) by loosening the holding screw (
10
).
Unscrew the upper head (
1
) and remove the fixed loading spring (
11
). Remove the upper body (
3
) by taking
out the 8 x 6 mm set screws (
½"
and
¾"
mixing valve); 8 x 8 mm set screws (1" and 1
½
" mixing valve). The
upper and lower bodies may be eased apart. All parts should now be cleaned using a proprietary de-scaler.
Note: Metal scrapers should not be used as this may cause permanent damage to the components.
Before reassembly please ensure that all sealing surfaces are clean ready to receive the new
gaskets and 'O' rings. (If the valve plug (6) is worn or damaged this should be replaced). Reassemble
the mixing valve and test for correct operation.
5. Maintenance