Types of Oils Used to Cool a Projection TV Tube

By Curtis Seubert

Updated September 28, 2017

Projection TV coolant must be changed regularly to ensure quality pictures.
i Image by Flickr.com, courtesy of Dan Taylor

Monoethylene glycol is the fluid most commonly used for cooling a projection TV tube. It can be purchased at most electronics stores or online.


Glycol is a chemical compound containing two hydroxyl groups. Glycol may also be referred to as “diol”.

Typical Uses of Glycol

Because monoethylene glycols have low freezing points and a high boiling points (the actual points depending on the surrounding air pressure and medium of containment), they are used in the production of anti-freeze, coolant and solvents.

Type of Coolant Used in TVs

Typically, rear projection TV manufacturers use an optical grade (99 percent pure) 70 percent mono denatured ethylene glycol and 30 percent glycerol/glycerine. The exact mixture may depend on the product and manufacturer. For example, Hitachi states that its optical coolant is "a combination of various chemicals" which are "[c]ustom manufactured and blended to meet customer specifications."

Location of Glycol in Your TV

You will find the glycol fluid in the “guns” of your TV—three projectors (red, green and blue) projecting different colored pictures onto your screen. Typically, the blue and green guns will need fluid changes more often than the red gun.


Glycol coolant (projection TV coolant) can be purchased at any major appliance or electronics store that sells projection screen TVs, or online. A 16 oz. bottle costs about $9. The type of coolant you purchase will not depend on your TV’s manufacturer; Phillips and Magnavox rear projection TVs, for example, use the same type of coolant.

Handling Glycol

Glycol is corrosive and toxic, so use gloves when handling. When changing or replacing the fluid in your TV, immediately wipe off any fluid that may have spilled onto other parts of your TV.