25mm stainless steel linear type
125mm staonless steel rotary type
250mm bronze rotary type

Self Acting Valves

The advantage of Walton self acting thermostatic control valves is that they are very robust and operate independently of external power supplies. They are therefore ‘fit and forget’. 

The valve contains a thermostatic element which expands at a pre-set temperature. This movement activates a control mechanism which proportions the system’s flow between the cooler and a bypass to maintain a constant system temperature. 

Sizes

Walton rotary self-acting valve bore sizes range from 25mm (1.00″) to 250mm (10.00″) diameter.

In addition a 25mm (1.00″) self-acting linear type valve is available which has a carbon or stainless steel body and stainless steel internal parts. The robust and simple construction of this valve makes it particularly suitable for the arduous conditions found in the offshore and petroleum industries.

The maximum flow rates that can be accommodated in each valve size are shown here.

Maximum flow rates in m3/hour

Valve Bore Fresh Water Sea Water Lub. Oil

25mm

10

10

10

40mm

22

16

16

50mm

35

26

26

65mm

60

45

45

80mm

90

67

67

100mm

100

75

75

125mm

160

120

120

150mm

180

180

180

200mm

400

290

290

250mm

600

450

450

Temperature ranges

The temperature that each valve maintains in operation is set during manufacture so that in practice any temperature between 14ºC and 95ºC can be controlled by selecting the most suitable thermostatic element and adjusting the control point as necessary.

An external lever allows the automatic mechanism to be overridden and the temperature to be controlled manually. The ability to control manually at a temperature lower than that being automatically maintained is of particular value when an individual section of the system is running ‘hot’, or in the unlikely event of an element failure.

Available temperature ranges

°C °F

10/20

50/68

14/26

57/79

20/30

68/86

22/30

22/30

27/40

10/104

31/42

88/108

37/47

99/117

40/50

104/112

43/54

110/130

°C °F

45/57

113/135

51/60

124/140

57/66

135/150

63/71

145/160

68/78

155/172

74/82

165/180

79/88

175/190

85/93

185/200

86/99

187/210

Port configuration

Self acting rotary valves can be supplied in any of six possible port configurations (called handings) to suit your preferred pipework layout. This provides great flexibility – the valve can be supplied to suit the pipework, rather than the pipework having to be adapted to suit the valve.

The six handings are shown in the diagrams on the right. The arrow on each diagram shows the direction of rotation of the valve’s rotor to open the Cooler port when the system heats up.

The 25mm (1.00″) linear type valve is supplied with a fixed port configuration of RI Handing which cannot be varied. If this is not suitable a 25mm (1.00″) rotary valve is available with the choice of all six handings.

LI Handing
LB Handing
LC Handing
RI Handing
RB Handing
RC Handing

System design

Mixing or diverting?

Walton valves may be installed to either mix fluids from two inlets and discharge through a single outlet (mixing), or to divide the flow from one inlet into two outlets (diverting).

 

When operating in mixing mode, the temperature control valve is fitted downstream of the cooler. The hot (bypass) and cold (cooler) fluid streams enter two valve ports in proportions determined by the position of the valve's rotor, thereby maintaining the temperature of the fluid leaving the third port within the operating range of the thermostatic element.

 

When operating as a diverter, the valve is fitted upstream of the cooler. The inlet from the heat source enters one port and is divided into two outlet streams to the cooler and bypass in proportions determined by the position of the valve's rotor. This maintains the temperature of the fluid returning to the heat source within the operating range of the thermostatic element.

 

In most applications it is recommended that the temperature control valve is fitted downstream of the cooler to operate as a mixing valve.

The valve may be installed in any attitude, gravity having no effect on its operation.

The system pipework should be as simple and compact as possible. The cooler by-pass pipe should be designed for minimal pressure loss. The pressure difference across the 3-way valve at full flow through either the cooler or cooler bypass should not exceed 0.8 bars.

 

A degree of flexibility in at least one of the connecting pipes is desirable although, if care is taken on installation, not essential. Mounting of the valve should be such that it is not subjected to excessive loading or vibration under running conditions.

 

For marine applications, temperature variations, pipe expansion and movement of the ship's hull should be taken into account when designing the piping runs and supports.

Mixing valve
(LI / RI Handing example shown)
Diverting valve
(LI / RI Handing example shown)

We are always willing to create a customised solution for your application if none of our standard products are suitable

Our advanced computer aided design software and the flexible nature of the Walton valve design mean that this can often be a cost-effective approach.

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