Data Sheet
Thermostatic operated water valve
Type FJVA
With built-in temperature sensor
Thermostatic operated water valves are used for the infinite, proportional regulation of flow quantity, depending on the setting and the sensor temperature.
The Danfoss range of thermostatic operated water valves includes a series of industrial products for both cooling and heating regulation. The valves are self-acting, i.e. they operate without the supply of auxiliary energy such as electricity or compressed air.
Because the valves constantly match flow quantity to demand they are especially suitable for temperature regulation.
The required temperature is maintained constant with no overconsumption of:
• Cooling water in cooling systems; hot water or steam in heating systems
• Thus operating economy is always reasonable
Features:
• Self-acting thermostatic operated water valve, which operates without auxiliary energy
• Opens on rising temperature of cooling water
• Valve opening degree is not aƒected by cooling water pressure diƒerential
• Hand regulation - unique option on the market, which saves installation time
• Regulating range defined for the point at which the valve begins to open
AI155286424361en-000401
Thermostatic operated water valve, Type FJVA
Functions
How it works?
When the three elements are built together and the valve is installed, the function sequence is as follows:
1.A temperature-dependent pressure - charge vapour pressure - builds up in the sensor.
2.This pressure is transferred to the valve via the bellows and acts as an opening or closing force.
3.The knob on the setting section and the spring exert a force that acts counter to the bellows.
4.When balance is created between the two opposing forces, the valve spindle remains in its position.
5.If the sensor temperature - or the setting - is changed, the point of balance becomes displaced and the valve spindle moves until balance is re-established, or the valve is fully open or closed.
6.On sensor temperature change the flow quantity change is approximately proportional.
7.The illustrations show an FJVA cooling water valve, but the function principle applies to all types of thermostatic valves.
Table 1: FJVA valves consist of three main elements
Setting section with knob, |
Valve body with ori€ce, |
Sensor in hermetically |
reference spring and setting scale. |
closing cone and sealing elements. |
sealed thermostatic element. |
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Applications
FJVA valves are for applications where, because of installation problems, etc., it is desirable to avoid using a capillary tube. This applies mainly where regulation accuracy requirements are more moderate and where an integral bypass can be accepted.
In FJVA the whole bellows element is used as the sensor. The valve reacts to the cooling water temperature and therefore it must always be installed in the return line. Thus, indirect regulation is involved.
To ensure the medium temperature to influence the thermostatic element, when the valve is closed, a by-pass in the valve (see Figure 1: Valve body with by-pass) provides a constant minimal flow through the valve.
Figure 1: Valve body with by-pass
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Valves of this type operate with significantly longer time constants than AVTA valves where the sensor is located at the point at which the temperature is to be regulated. FJVA is mainly used in systems where large and sudden load changes do not occur.
© Danfoss | Climate Solutions | 2021.03 |
AI155286424361en-000401 | 2 |
Thermostatic operated water valve, Type FJVA
Product specification
Materials
Figure 2: Materials connected with FJVA
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2 |
3 |
4 |
5 |
1 |
2 |
Table 2: Materials - parts in contact with the medium
No. |
Description |
Material |
1 |
Spindle |
Brass |
2 |
Diaphragms |
Rubber - ethylene - propylene (EPDM) |
3 |
Valve body and other metal parts |
Forged brass |
4 |
Valve cone |
Nitrile rubber (NBR) |
5 |
Valve seat |
Stainless steel |
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Installation
Figure 3: FJVA installation
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The valves can be installed in any position. An arrow on the valve body indicates the direction of flow. FJVA valves are also marked so that the letters RA can be read straightforwardly. The installation of an FV filter ahead of the valve is recommended.
If a mounting bracket is used - see Spare parts and accessories - it must always be between valve body and setting section (see illustration).
© Danfoss | Climate Solutions | 2021.03 |
AI155286424361en-000401 | 3 |
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