Spirax Sarco MkII Guide

IM-P157-38 CMGT Issue 4 1
Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
These instructions should be read by the Company Safety Officer
1. General safety information
2. General product information
3. How to size
4. Installation
5. Maintenance
6. Spare parts
7. Fault finding

Steam/Water Mixing Stations
(MkII valves - 2002 onwards)
Safety and Operation
Installation and Maintenance Instructions
IM-P157-38
CMGT Issue 4
© Copyright 2020
Printed in GB

IM-P157-38 CMGT Issue 4
2
Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation

IM-P157-38 CMGT Issue 4 3
Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
Safe operation of the unit can only be guaranteed if it is properly installed, commissioned and
maintained by a qualified person (see Section 11 of the attached Supplementary Safety Information)
in compliance with the operating instructions. General installation and safety instructions for
pipeline and plant construction, as well as the proper use of tools and safety equipment must
also be complied with.
1.1 Pressure
Before attempting any maintenance of any component of the steam/water mixing station consider
what is or may have been in the pipeline. Ensure that any pressure is isolated and safely vented
to atmospheric pressure before attempting to maintain any component, e.g. mixing valve, hose
etc. This is easily achieved by fitting Spirax Sarco depressurisation valves type DV (see separate
literature for details). Discharge contents of the hose and station by pulling the gun trigger and
eliminate pressure until water flow stops. Do not assume that the system is depressurised even
when the pressure gauge indicates zero.
1.2 Temperature
Allow time for temperature to normalise after isolation to avoid the danger of burns. For personal
protection wear protective clothing, especially heavy duty gloves and safety glasses.
PTFE:
If parts made from PTFE have been subjected to a temperature approaching 260 °C (500 °F) or
higher, they will give off toxic fumes, which if inhaled are likely to cause temporary discomfort.
It is essential for a no smoking rule to be enforced in all areas where PTFE is stored, handled, or
processed as persons inhaling the fumes from burning tobacco contaminated with PTFE particles
can develop 'polymer fume fever'.
Viton:
If parts made from Viton have been subjected to a temperature approaching 315 °C (599 °F) or
higher, it may have decomposed and formed hydrofluoric acid. Avoid skin contact and inhalation
of any fumes as the acid will cause deep skin burns and damage the respiratory system.
1.3 Disposal
The product is recyclable. No ecological hazard is anticipated with the disposal of this product
providing due care is taken, except;
PTFE:
-Can only be disposed of by approved methods, not incineration.
-Keep PTFE waste in a separate container, do not mix it with other rubbish, and consign it to
a landfill site.
Viton:
-Can be land filled, when in compliance with National and Local regulations.
-Can be incinerated, but a scrubber must be used to remove Hydrogen Fluoride, which is evolved
from the product and with the compliance to National and Local regulations.
-Is insoluble in aquatic media.
1. Safety information

IM-P157-38 CMGT Issue 4
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Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation

This product must only be installed and commissioned by qualified personnel
(see Section 1.5).
The hosedown station includes a safety device called the TCO1. This temperature cut-out valve
activates at a temperature of 95 °C (203 °F) to limit the discharge of steam in the event of a system
fault. This assumes 20 m (65.6 ft) hose installed - shorter length hoses may result in a brief discharge
of steam following activation of the TCO1.
The mixing valve 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.
Always operate the hosedown station as instructed on the warning notice sent out with the
equipment; particularly regarding protective clothing. The WARNING NOTICE must always be
displayed by the mixing valve.
1.5 Qualified personnel
For the purposes of these operating instructions qualified personnel are persons who are
experienced in the installation, commissioning and operation of this product and who are suitably
qualified to perform their duties, e.g.:
-Have received training or instruction in the maintenance and use of appropriate safety equipment
according to current safety standards.
-Have received training in first-aid.
1.6 Safety test procedure
A safety check undertaken by qualified personnel must be carried out each time the unit is used.
The safety test and subsequent maintenance procedure ensures that live steam cannot be
discharged from the gun, which would happen in the event of e.g. a seized piston.
Due to the possible presence of steam, please ensure due care and attention are observed when
undertaking this task. Wear protective clothing, especially heavy duty gloves and safety glasses.
With the cold water inlet valve shut and the steam inlet valve open, carefully operate the gun. Before
pulling the trigger, hold the gun firmly in both hands and adopt a body position which will prevent
loss of balance due to recoil from the hose gun.
There should be no flow observed at the gun. If steam flow is detected during the test, or the
TCO1 activates, the hosedown station, it must be taken out of service immediately. Please refer
to Section 5, 'Maintenance'.
The above test must be repeated after maintenance to the steam/water mixing valve.

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Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
1.7 Danger of injury
Should you intend to use Spirax Sarco products for new or not tested fluids or for applications
not described in Spirax Sarco product information please contact the Spirax Sarco applications
department or our local sales engineer for written advice.
All hose and gun assemblies are to be tested for operational safety from time to time. This should
include a daily visual inspection. If damage occurs (this also applies to the hose cover) the hose
and gun assemblies must be renewed, for safe working.
The same constant vigilance should also be applied to the valve and its fittings and the hosedown
gun.
The mixing valve must always operate 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.

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Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
2.1 General information
Note: These Installation and Maintenance Instructions are for MkII systems/
valves supplied from the year 2002 onwards. For earlier valves, see separate
Installation and Maintenance Instructions IM-P157-03.
Design
The Spirax Sarco steam/water mixing station is designed to provide hot water economically by blending
steam and cold water quickly to the required user temperature. This temperature can be altered by turning
the temperature adjustment knob. As the valve is not thermostatically controlled, in order to maintain a fixed
hot water temperature the cold water pressure and flowrate must be constant. The temperature cut-out valve
TCO1 will limit any steam supply from the mixing valve in the event of a system fault.
Operation
The mixing valve employs a piston to lift and open the steam valve. The piston is lifted by the cold water
supply. If the cold water supply stops the piston will fall, closing the steam valve.
Maintenance
This operation can only occur if the piston is free to move. Scale will seize the piston and the valve must be
maintained and cleaned regularly to prevent scale build-up and ensure safe valve operation. This is especially
important in hard water areas. The pressure gauges supplied with the mixing station are installed in the steam
and cold water supply lines to aid fault finding.
Ancillaries
Each steam/water mixing station is supplied with isolation valves, check valves, union joints, steam trap,
strainers (with 100 mesh stainless steel screens), pressure gauges, syphon and cocks, thermometer and
temperature cut-out valve (see Figure 1).
Note: For further information see the following Technical Information Sheets:
TI- P157- 05 Hosedown gun, hose and hose rack
TI- P157- 06 Steam/water mixing stations
TI- P157- 08 Steam/water mixing valve
TI- P157-18 TCO1 temperature cut-out valve
These sheets give full details of:- Materials, sizes and pipe connections, dimensions, weights, operating
ranges and capacities.
2. General product information

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Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
Fig. 1 ¾" and 1½" assembly shown
Steam
inlet
Steam
inlet
Cold
water
inlet
Cold
water
inlet
Hot water outlet
†
Inter connecting pipe is not supplied with the mixing valve station. This pipe should be at least 0.5 m (19.3")
long to prevent condensate backing up into the steam line.
†
½" and ¾"
station only
½" and ¾"
station only
1½" station only1½" station only

IM-P157-38 CMGT Issue 4
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Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
2.2 Technical data
2.2.1 Minimum flow (to open the steam valve) and spring selection chart
(see Table 1)
A restricted outlet can cause back pressure, reducing the water flow through the mixing valve which may
prevent a sufficient amount of steam entering the mixing chamber.
The minimum flow for each size of mixing valve is shown in Table 1 below.
Note: when a valve supplies water against a back pressure a minimum pressure drop of approximately
1 bar (14.5 psi) is required across the mixing valve to allow the steam valve to lift off its seat.
Table 1
Size Spring
value
Spring
colour
code
*
Steam pressure Min. flow to
open steam
valve
Spring
notch
marking
psi bar kg/cm2g/min l/min
½"
High Y 100 - 150 7. 0 0 - 10.3 7.14 - 10.51 1.0 4.5 Three
Medium G 50 - 100 3.50 - 7.0 3.57 - 7.14 0.6 2.7 Two
Low Bl 5 - 50 0.35 - 3.5 0.36 - 3.52 0.5 2.3 One
¾"
High R 100 - 150 7. 0 0 - 10.3 7.14 - 10.55 1.8 8.2 Three
Medium B 50 - 100 3.50 - 7.0 3.57 - 7.14 1.5 6.8 Two
Low W 5 - 50 0.35 - 3.5 0.36 - 3.52 6.0 6.8 One
1"
High R 100 - 150 7. 0 0 - 10.3 7.14 - 10.51 8.0 36.3 Three
Medium B 50 - 100 3.50 - 7.0 3.57 - 7.14 7.0 31.8 Two
Low W 5 - 50 0.35 - 3.5 0.36 - 3.52 6.0 2 7. 2 One
1½"
High R 100 - 150 7. 0 0 - 10.3 7.14 - 10.51 12.0 54.4 Three
Medium B 50 - 100 3.50 - 7.0 3.57 - 7.14 12.0 54.4 Two
Low W 5 - 50 0.35 - 3.5 0.36 - 3.57 12.0 54.4 One
*Y = Yellow
G = Green
Bl = Black
R = Red
B = Blue
W = White

IM-P157-38 CMGT Issue 4 9
Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
2.3 Options for ½" and ¾" steam/water mixing stations
2.3.1 Hose
Temperature
range
-30 °C to +170 °C (-22 °F to +338 °F) for saturated steam
95 °C (203 °F) for continual hot water operation
Safety factor 10:1 for steam, 3.15:1 at 18 bar (261 psi) working pressure
Lining EPDM rubber, white, smooth, compounded using FDA approved ingredients
Reinforcement High strength synthetic textile
Cover EPDM rubber, blue, weather, ozone and abrasion resistant
Identification Type 1 Continuous
longitudinal white
band
T739 WP 7 bar (101.5 psi)
170 °C (338 °F)
Type 2 White band ARCO 39174 - FDA, Food/steam 7 bar
170 °C
2.3.2 Hosedown gun
There are two sizes of hosedown gun; the ½" gun used with the ½" hose and ½" steam/water mixing station.
Similarly the ¾" gun used with the ¾" hose and ¾" steam/water mixing station. Hosedown guns and hoses
should never be used with 1" and 1½" steam/water mixing stations (see Figure 2).
Temperature 100 °C (212 °F)
Maximum pressure 10 bar g (145 psi g)
Capacity With wide spray 42 l/min at 5 bar (9.25 gal/min at 72.5 psi)
With jet spray 25 l/min at 5 bar (5.50 gal/min at 72.5 psi)
Capacities (approximate)
Litres/minute
Supply pressure bar g
Fig. 2

IM-P157-38 CMGT Issue 4
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Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
500
400
300
200
100
0
0 1 2 3 4 5 6 7 8 9 10
40 °C
50 °C
60 °C
70 °C
80 °C
90 °C
350
300
200
100
0
0 1 2 3 4 5 6 7 8 9 10
40 °C
50 °C
60 °C
70 °C
80 °C
90 °C
100
75
50
25
0
0 1 2 3 4 5 6 7 8 9 10
40 °C
50 °C
60 °C
70 °C
80 °C
90 °C
200
150
100
50
0
0 1 2 3 4 5 6 7 8 9 10
40 °C
50 °C
60 °C
70 °C
80 °C
90 °C
100
75
50
25
0
0 1 2 3 4 5 6 7 8 9 10
40 °C
50 °C
60 °C
70 °C
80 °C
90 °C
Supply pressure bar g
(Please note: Only SI metric figures have been used in this section)
The graphs indicate the maximum flow of hot water at various temperatures for a given steam supply pressure.
The bold line shows the maximum cold water flow for a given water supply pressure. When sizing the valve,
ascertain the hot water temperature and quantity required, and the water and steam pressure available. The
cold water and steam supply pressure should be nominally equal for satisfactory operation.
Plot the cold water supply pressure and read off from the bold line the maximum flow of cold water. Plot the
steam supply pressure against the running temperature required and read off the maximum flow of heated
water. For sizing purposes always select the lowest of the two values because depending on the supply
pressures, there can be an imbalance in the amount of either water or steam heat available. The effect of
selecting different supply pressures or different sizes of valve can easily be compared.

l/min. then the ½
need to select a ¾" mixing valve (although the ½" mixing valve can pass 40 l/min of cold water), since the

Sizing example:
For cold water supply pressure of 3 bar g
the maximum flow of cold water is 40 l/min.
For steam supply pressure of 3.5 bar g the
maximum flow of hot water at 50 °C is 32 l/min.
Supply pressure bar g
3. How to size