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Spirax Sarco MkII, Safety And Operation

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Spirax Sarco MkII Safety And Operation Download Page 43

IM-P157-38 

CMGT Issue 4

43

Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation

Symptom

Cause and corrective action

TCO1 operates

Hot water temperature 

too high

Inspect and service valve

If the internals of the mixing valve are free of scale or the valve has just been 

serviced or is new, check the following:

Constant cold water pressure

a) 

The mixing valve should be supplied with a constant cold water pressure. If 

this supply fluctuates, the mixed hot water temperature could rise above 95 °C 

(203 °F) and the TCO1 will be activated.

This could occur on valves that are installed off the mains. This installation has 

now been banned by the U.K. Water Authorities. If a booster pump is being 

used to supply an adequate constant cold water supply pressure, then pressure 

switches must not be used, since this can affect the operation of the steam/

water mixing valve station. Installation of a balanced line arrangement should 

be considered; (a typical layout is shown in Figure 12, page 17).

Difference in supply pressures (see page 12)

b) 

When a mixing valve is supplied with a higher steam pressure compared to 

a lower cold water pressure, in some instances it is possible to produce hot 

water in excess of 95 °C (203 °F). It is also possible that steam can exit the 

mixing valve as the steam valve can remain open in some instances, if the 

supply pressures are not nominally equal.

A BRV pressure reducing valve would need to be installed in the steam line to 

reduce pressure. This is why we recommend that the supply pressures are 

nominally equal.

Summary of Contents for MkII

Page 1: ... 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 1570950 4 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 ...

Page 2: ...IM P157 38 CMGT Issue 4 2 Steam Water Mixing Stations MkII valves 2002 onwards Safety and Operation ...

Page 3: ...nger 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 pr...

Page 4: ...re 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 ...

Page 5: ...e 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 reachi...

Page 6: ...fted 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 wit...

Page 7: ...embly 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 and station only and station only 1 station only 1 station only ...

Page 8: ...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 cm2 g min l min High Y 100 150 7 00 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 High R 100 150 7 00 10 3 7 14 10 55 1 8 8 2 Three Medium B 50 100 3 50 7 0 3 57 ...

Page 9: ...nd 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 gun used with the hose and steam water mixing station Similarly the gun used with the hose and steam water mixing station Hosedown guns and hoses should never be used wit...

Page 10: ... 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 In the example s...

Page 11: ...00 200 100 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 Steam water mixing valve capacities Litres minute Litres minute Supply pressure bar g Supply pressure bar g Litres minute Supply pressure bar g Litres minute Supply pressure bar g ...

Page 12: ... the steam to water pressure ratio must not exceed 3 1 It is advisable that the cold water pressure does not exceed the steam pressure as this will inhibit the ability of the valve to produce hot water If there is a restriction on the outlet e g hosedown gun pipework or hose control or isolation valve etc the steam pressure and water pressure must be nominally equal 1 Turn the ball valves to isola...

Page 13: ...IM P157 38 CMGT Issue 4 13 Steam Water Mixing Stations MkII valves 2002 onwards Safety and Operation 12 15 8 10 11 9 3 Steam inlet 2 1 Cold water inlet Fig 3 ...

Page 14: ... the bypass valve fully anticlockwise 14 Turn the adjustment knob fully anticlockwise coldest setting 15 Turn on the water and steam then hold the gun open see Start up Section 4 4 1 Check the hot water temperature Turn the bypass valve 8 clockwise until either the temperature is just below that required or the flow has been reduced significantly Note It is normal for the flowrate to decrease thro...

Page 15: ...IM P157 38 CMGT Issue 4 15 Steam Water Mixing Stations MkII valves 2002 onwards Safety and Operation 12 15 8 10 11 9 3 Steam inlet 2 1 Cold water inlet Fig 3 ...

Page 16: ... T piece K push the thermometer E into the pocket L and lock in place with the grub screw tighten the pocket into the reducing bush To connect the hot water supply pipework to the hot water outlet of the steam water mixing valve first screw the thermometer T piece and TCO1 to the hot water pipe This arrangement should then be attached to the steam water mixing valve using the hot water outlet unio...

Page 17: ...N and station only G A B D H I P Q R Q R K K I L M K E Steam inlet Cold water inlet Hot water outlet D I I I F S 1 steam water mixing valve F B 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 Fig 4 ...

Page 18: ...Description Used on 1 1 Elbow 1 2 2 Union 1 2 Barrel nipple 3 8 1 9 9 1 10 1 10 Reducing nipple x 3 8 1 x 3 8 1 1 1 x 1 2 1 x 1 Equal T 3 1 4 1 3 1 4 Reducing T 1 x 1 Reducing bush x 1 1 1 1 x 1 1 x 4 x 3 8 1 x 3 8 1 1 1 x 3 8 2 N Temperature cut out valve and station only O Reducing nipples P Ring syphon Q Cock R Pressure gauge S Steam trap H M F unions I Nipples J Red handle cover K T piece L Th...

Page 19: ...pe 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 Fig 5 Packing list O A J B K H N and station only G A B D H I P Q R Q R K K I L M K E Steam inlet Cold water inlet Hot water outlet D I I I F S 1 steam water mixing valve F B ...

Page 20: ...stalled between the pressure gauge T piece and the mixing valve union in the steam and cold water supply lines This will take account of the smaller overall dimension of the replacement valve Connect the pipework fittings according to Figure 4 using a suitable thread sealing medium The TCO1 is installed between the hot water outlet of the mixing valve and the equal T that houses the thermometer Th...

Page 21: ...tic head to supply minimum cold water pressure of 3 bar g 43 5 psi g Steam main Incoming steam supply Thermostatic steam trap Cold water supply Cold water feedtank Hot water out 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 30 m 98 5 ft static head ...

Page 22: ...ft long connection hose supplied with the self retracting hose reel The heavy duty gun is fixed to the hose using the swivel coupling see Figures 9 10 and 11 The swivel coupling is connected to the hose as a complete item It must be separated into two pieces so that the gun retaining can be correctly torqued into the gun Fig 9 Unscrew the retaining nut from the hose tail using 15 16 A F and 7 8 A ...

Page 23: ...gulations with regard to direct use of mains water supply A break tank may be required to to provide an air gap for each valve If a booster pump is being used to supply an adequate constant cold water supply pressure then pressure switches must not be used since this can affect the operation of the steam water mixing valve station Installation of a balance line arrangement should be considered a t...

Page 24: ...l water flow stops 4 4 2 Setting temperature Once correctly installed the temperature is adjusted as follows refer to Figure 14 a Remove the temperature adjustment knob retaining screw 10 and turn the temperature adjustment knob 12 fully clockwise b Remove the adjustment knob and replace making sure that the retaining screw location is just anticlockwise of one of the two location stops c Replace ...

Page 25: ...ards Safety and Operation Steam inlet Cold water inlet Fig 13 and hosedown station Interconnecting 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 Alternative hot water outlet ...

Page 26: ...ve plug 7 Steam valve seat 8 Bypass valve 12 14 15 8 10 11 9 3 Steam inlet 5 4 2 1 7 13 16 Cold water inlet 6 17 18 19 21 20 9 Bypass screw 10 Temperature adjustment knob retaining screw 11 Fixed loading spring 12 Temperature adjustment knob 13 Body O ring 14 O ring packing washer 15 Top gasket 16 Bypass valve washer 17 Wall bracket 18 Cap screw 19 Washer 20 Bypass valve O ring 21 Spigoted spring ...

Page 27: ...eration 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...

Page 28: ...w 9 remove the bypass valve 8 and refit with the replacement parts Replace the bypass valve washer 16 7 Remove the upper retaining cap using a two prong tool or 11 16 A F box spanner The piston is free to rotate The piston must therefore be held in order to remove the upper retaining cap This is achieved by placing 2 x diameter Tommy bars through the holes in the piston at 180 to each other 8 Lift...

Page 29: ...valve b The steam silencer plate is fitted with the three rivet heads against the PTFE valve seat housing assembly 7A i e rivets not visible c The piston moves freely up and down before fitting the springs and final assembly d When refitting the upper body 3 the 8 x cap screws 18 should be tightened progressively Note Thermometer is replaced by simply loosening the grub screw in the pocket removin...

Page 30: ... seals The swivel coupling should be periodically inspected e g during routine maintenance procedures for evidence of wear on the internal seals During normal usage the swivel action of the coupling acts upon these seals and a slight leakage may occur if the seals are allowed to wear excessively Under normal operating conditions the seals should be replaced every two years Separate the hose tail f...

Page 31: ...e Separate here 7 8 A F spanner 15 16 A F spanner Gun Torque setting 50 N m 37 lbf ft 5 Unscrew the gun from the retaining nut using an 11 16 A F spanner on the spanner flats of the retaining nut Tighten to 50 N m 37 lbf ft On older units insert a 12 mm A F hex allen socket into the gun handle to a torque of 50 N m 37 lbf ft Fig 17 Fig 18 Cut here Hose Hose tail of swivel coupling 6 Remove the hos...

Page 32: ... spanner Fig 23 7 The swivel coupling is supplied as a complete item Separate into two pieces by unscrewing the hose tail using 15 16 A F and 7 8 A F spanners 8 A thread sealant or PTFE tape should be applied to the male thread of the gun retaining nut Screw the retaining nut into the gun using an 11 16 A F spanner to 50 N m 37 lbf ft On older units a 12 mm allen drive socket is required 9 Push ne...

Page 33: ...un in for example a vice by clamping the rear end of the body and ease the cover over the front of the gun 7 Unscrew the nozzle from the gun body 8 Remove the end screw from the rear of the gun The end cap will be loose in the gun body Remove the piston a and b and the spring from the gun body 9 Remove the top screw from the top of the gun body so that the cylinder can be taken out of the gun body...

Page 34: ...tand the reason for the failure This should then be rectified before replacing the TCO1 element so that failure does not occur again 1 Isolate the steam and cold water supplies by closing the two ball valves 2 Discharge the contents of the hose and station by pulling the gun trigger and eliminate pressure until the water flow stops 3 Undo the cap from the body using a 1 A F spanner and remove the ...

Page 35: ...rigger and eliminate pressure until the water flow stops 3 Remove the hose by splitting the union and unscrew the thermometer T from the mixing valve hot water inlet Remove the nipple from the valve end of the T piece 4 Assemble the TCO1 retro fit pack Screw the 1 x reducing nipple into the TCO1 marked INLET for the mixing valve for the mixing valve it is a 1 x reducing nipple Screw the 1 x reduci...

Page 36: ...hrough the holes in the piston 4 and through the holes in the steam valve housing Note the piston 4 will have to be raised slightly to align this 10 Remove the crinkle and pressure washers and PTFE seat 11 To reassemble do the reverse of the break down procedure Before reassembly please ensure that all sealing surfaces are clean ready to receive the new gaskets and O rings Reassemble the mixing va...

Page 37: ...TFE seat Crinkle washer Pressure washer Steam valve housing Fig 27 Gland nut Note The 1 body 3 has internal female threads shown the 1 has external male threads 20 1 11 21 2 Notes i The torque setting for the upper head 1 to the upper body 3 is 180 200 N m 245 272 lbf ft ii The torque setting for the steam valve housing to the lower body 5 is 50 56 N m 37 41 lbf ft ...

Page 38: ...er spares The spare parts available are detailed in this Section No other parts are supplied as spares Example 1 off Maintenance kit for steam water mixing valve Note For hosedown station ancillaries please see separate TI s 6 1 Mixing valve spares Maintenance kit 2 6 7 8 13 14 15 20 Gasket set 13 14 15 16 20 Fixed loading spring 11 15 20 2 6 Spare parts ...

Page 39: ...ations MkII valves 2002 onwards Safety and Operation 1 2 3 6 2 Thermometer spares Thermometer set 2 3 Thermometer 1 6 3 Hose spares Swivel coupling 1 Fig 29 Fig 30 1 6 4 Hosedown gun spares Rubber cover for gun body 1 Internal spares kit 2 1 2 Fig 31 ...

Page 40: ...8 CMGT Issue 4 40 Steam Water Mixing Stations MkII valves 2002 onwards Safety and Operation 6 5 TCO1 spares Element 1 1 Fig 32 6 6 Retro fit pack TCO1 temperature cut out valve 1 Reducing nipples 2 Fig 33 2 2 1 ...

Page 41: ...t check valve is installed with direction of flow arrow in the right direction Ensure that the check valve cone is free to move Fixed loading spring Check that the correct fixed loading spring 11 is fitted Replace with the lower rated spring if necessary Hot water outlet temperature too low Fixed loading spring Check that the correct fixed loading spring 11 is fitted Replace with low the lower rat...

Page 42: ...t water temperature will also vary accordingly This would occur where there are take offs prior to the mixing valve If the supply cold water pressure or flowrate falls the hot water temperature will rise For sites known to have intermittent cold water supplies a feedtank and booster pump should be considered This is very important in the U K where an air gap is required using a feedtank after chan...

Page 43: ...rities If a booster pump is being used to supply an adequate constant cold water supply pressure then pressure switches must not be used since this can affect the operation of the steam water mixing valve station Installation of a balanced line arrangement should be considered a typical layout is shown in Figure 12 page 17 Difference in supply pressures see page 12 b When a mixing valve is supplie...

Page 44: ...IM P157 38 CMGT Issue 4 44 Steam Water Mixing Stations MkII valves 2002 onwards Safety and Operation ...

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