Monthly Archives for January 2011

HVAC Level-Master Control Installation

The level-master control is applicable to any system that has been specifically designed for flooded operation. The valve is usually connected to feed into the surge drum above the liquid-level. It can feed into the liquid leg or coil header. … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: | Leave a comment

HVAC Level-Master Control

The level-master control is a positive liquid-level-control device suitable for application to all flooded evaporators (see Fig. 11-45). The level-master control is a standard thermostatic-expansion valve with a level-master element. The combination provides a simple, economical, and highly effective liquid-level … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: | Leave a comment

Level Control Valves Float valve

A hollow float is sometimes used to control the level of refrigerant (see Fig. 11-43). The float is fastened to a lever arm. The arm is pivoted at a given point and connected to a needle that seats at the … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: , | Leave a comment

Level Control Valves Capillary tubes

Capillary tubes are used to control pressure and temperature in a refrigeration unit. They are most commonly used in domestic refrigeration, milk coolers, ice-cream cabinets, and smaller units. Commercial refrigeration units use other devices. The capillary tube consists of a … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: , | Leave a comment

Discharge-Bypass Valves Hot Gas

Hot gas may be required for other systems functions besides bypass capacity control. Hot gas may be needed for defrost and head pressure control. Normally, these functions will not interfere with each other. However, compressor cycling on low suction pressure … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: | Leave a comment

Discharge-Bypass Valves Testing and Operating Pressures

Excessive leak testing or operating pressures may damage these valves and reduce the life of the operating members. Since a high-side test pressure differential of approximately 350 psi or higher will force the DBV open, the maximum allowable test pressure … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: | Leave a comment

Discharge-Bypass Valves Installation

Bypass valves can be installed in horizontal or vertical lines, whichever best suits the application and permits easy accessibility to the valves. However, consideration should be given to locating these valves so that they do not act as oil traps. … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: | Leave a comment

Bypass to Evaporator Inlet without Distributor

On many applications, it may be necessary to bypass directly into the suction line. This is generally true of systems with multi evaporators or remote-condensing units. It may also be true for existing systems where it is easier to connect … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: | Leave a comment

Externally Equalized Bypass Valves

The primary function of the DBV is to maintain suction pressure. Thus, the compressor suction pressure is the control pressure. It must be exerted on the underside of the valve diaphragm. When the DBV is applied as shown in Fig. … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: | Leave a comment

Discharge-Bypass Valves Application

DBVs provide an economical method of compressor capacity control in place of cylinder unloaders or of handling unloading requirements below the last step of cylinder unloading. On air-conditioning systems, the minimum allowable evaporating temperature that will avoid coil icing depends … Continue reading

17. January 2011 by admin
Categories: Controlling Refrigerant | Tags: | 1 comment

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