Sight Glass
A sight glass is a device installed partway down a pipe to enable an external visual check through a glass window of the approximate condition of fluids running inside the pipe or tank. Generally, this product is used to check the dryness of liquefied refrigerant gas. Other products are more elaborate, with some types that facilitate the checking of the fluid flow by oscillating a ball (float) or opening and closing a flapper. A lantern type that enables fluid flow checking from all 360° directions is also available. Various connection methods are used compatible with different pipes and tanks, including flange connection, wall welding, screw-in connection, butt welding and socket welding. Reinforced glass is sometimes used for the glass area depending on the application. However, since deterioration and abrasion of this glass cannot be avoided, it must be replaced approximately every year with a new part to prevent accidents caused by glass damage.