Sight glasses

What are the liquid sight glasses in the refrigeration system for?

The liquid sight glass is an extremely important element for the installer. With its help, observing whether bubbles appear in it, you can initially assess the condition of the installation. In principle, each built cooling system should be equipped with a sight glass with a chemical moisture indicator. The sight glass is usually mounted on the liquid line directly in front of the throttle element. Only the liquid refrigerant, without bubbles, guarantees proper operation of both the thermostatic element and the entire system. The vapor bubbles are the effect of primary or secondary refrigerant shortage in the system.

Inadequate filling of the installation is the cause of the initial shortage, while the reason for the secondary shortage is usually the following reasons:

-The pressure losses in the liquid line, in the elements of the fittings, filters-driers and other components of the installation (and thus the flow resistance),
- Excessive heat exchange between the liquid line and the room through which it is carried out, causes partial evaporation of the liquid refrigerant (improper pipe insulation),
- Too big a difference in height (and associated pressure losses) between the condenser and the evaporator,
- Sucking a large amount of refrigerant into the evaporator resulting from its strong frost.

To prevent these problems, pressure losses, eliminate throttling causes, obstructions, properly isolate liquid lines and fittings, or reduce the temperature in the condenser.

The Castel's specular sight glasses found in our offer are standard equipped with a chemical indicator of moisture. The colors presented by the indicator indicate the following states of the refrigerant (irrespective of the type and temperature of the refrigerant):

- Green color - dry agent

- Yellow color - moistened agent