Hollow float is sometimes used to control the level of refrigerant (see Fig. 11-43). The float is mounted on the lever. Hand mixed in a given point, and is connected to a needle that places at the opening of the valve. If there is no liquid in the evaporator, the ball-lever arm rests to a stop, and the needle is not seated, thus leaving it the valve is open. As soon as the liquid refrigerant under pressure compressor enters the float chamber, the float rises with the level of the liquid until, at a given level, needle closes the needle valve opening.
In some of the larger stations, where CFC-12 as a refrigerant, several port for handling of large quantities of fluid.
Installation. The following precautions must be met before installing the float valve:
Most float management are designed for a maximum differential pressure of 200 pounds.
If the pressure exceeds 190 pounds, there are the stems of estuaries and special size available for low temperature applications.
In any application, save the alignment bottom line above the bottom of the evaporator oil to avoid logging.
Make sure there are no traps in the alignment of the line.
The stems of the ball valve must be in a horizontal plane.
The flow of refrigerant must be not less than 100 m/min, where the bottom float alignment connect to the header or the return of the battery.
This means that the upper and battery pipes must be of a suitable size.
Batteries of small diameter with a speed more than 50 fpm not be used for precise application float. However, the float can control within a wide range with higher speeds. Top alignment connection must be connected to the point of almost zero speed gas.
In automatic factories, always give a solenoid valve in the liquid line ahead float management. This solenoid valve to close or at a temperature are in a satisfactory condition or by stopping the compressor.
Fig. 11-44 shows the connections pressure float management. There have been new developments in the control of liquid level since the first days of cooling.
Controls and Other Circuit Components 
