Category Archives for Valves & Controls

Superheat Controlled Valves For Industrial Refrigeration

The superheat-controlled expansion valve needs no defense in its use in comfort air conditioning applications and in commercial refrigeration, but it is appropriate now to examine its applicability to industrial refrigeration systems. Many respected industrial refrigeration professionals have in the … Continue reading

16. May 2018 by Jim
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Superheat Controlled Expansion Valves

Probably the most widely used flow control device in general refrigeration practice, including air conditioning, is the superheat-controlled expansion valve. The valve is popularly called a thermostatic expansion valve, a name that implies controlling a fixed evaporating temperature. The valve … Continue reading

16. May 2018 by Jim
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Proper Placement Of The Float Chamber

It would be possible to install a float or a capacitance probe directly in the vessel, but it is highly preferable to attach a float or capacitance chamber external to the vessel. One reason is that the level in the … Continue reading

16. May 2018 by Jim
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Capacitance Level Sensor

Electrical capacitance between two plates is the electrical charge divided by the voltage difference needed to maintain this charge. A capacitance level sensor measures the capacitance between the center rod and the column in Fig. 11.12. When the liquid level … Continue reading

16. May 2018 by Jim
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Liquid Level Controls – Mechanical And Float Switch

Numerous types of level controllers are used in industrial refrigeration practice, two important types of which are shown in Fig. 11.11. The mechanical type in Fig. 11.11a is a simple one applicable for smaller systems. As the liquid level rises, … Continue reading

16. May 2018 by Jim
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Liquid Level Controls High and Low Side Float Valves

Two major categories of liquid-level controllers used in industrial refrigeration systems are (1) high-side float valves, and (2) low-side float valves. These classes of valves, as shown schematically in Fig. 11.10, differ in the placement of the valve. The flow … Continue reading

16. May 2018 by Jim
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Pressure Regulating Valves – Direct Acting, Pilot Operated And Externally Compensated

There are frequent situations where refrigerant flow controls must regulate pressure; several are illustrated in Fig. 11.8. Controlling the pressure in the evaporator, as in Fig. 11.8a, may be required in two different situations. It may be necessary to prevent … Continue reading

16. May 2018 by Jim
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Gas Powered Suction Stop Valves

In low-temperature installations the shutoff valve between the evaporator and the suction line should offer as little flow resistance as possible during refrigeration. A normally-open valve meets this requirement, but in addition the valve must be capable of closing positively, … Continue reading

16. May 2018 by Jim
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Pilot Operated And Gas Pressure Operated Solenoid Valves

To make the solenoid valve practical for large pipe diameters, concepts must be applied other than direct force on the valve stem from the magnetic coil. Two approaches are pilot-operated and gas-pressure-operated valves. In the pilot operated valve, a small … Continue reading

16. May 2018 by Jim
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Direct Acting Solenoid Valves

Solenoid valves are electrically operated shutoff valves. Probably the most common is the normally closed (NC) valve, but normally open (NO) valves are also available4. With both types, system pressure works to keep the valve closed when that position is … Continue reading

16. May 2018 by Jim
Categories: Valves & Controls | Comments Off on Direct Acting Solenoid Valves

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