RHT Pex Tubing Specifications

PEX, or cross-linked polyethylene, is a strong yet flexible pipe commonly used in commercial and residential plumbing installations. RHT, or radiant heat tubing, is a composite PEX that is used in radiant flooring. RHT PEX, also known as PEX-B, is created through an extrusion press and then strengthened using a moisture cure method that is referred to within the industry as the silane method. This process establishes cross-linking by way of silanol condensation. Silanol condensation creates strong molecular bonds between polyethylene molecules and gives RHT PEX the same strength as PEX-A.


RHT PEX is available in a variety of sizes from 1/4 inch all the way up to large 4-inch tubing. Size designations are based upon the outside diameter of the pipe, the most common of which are 3/8 inch, 1/2 inch, 3/4 inch, and 1 inch. The inside diameter of 3/8 inch pipe averages 0.35 inches and the inside diameter of 1/2 inch pipe measures an average of 0.475 inches. Similarly, 3/4 inch RHT PEX pipe has an inside diameter of 0.574 inches and 1 inch pipe averages 0.862 inches inside diameter.

Pressure Ratings

Under normal operating temperatures, those not exceeding 73 degrees Fahrenheit, RHT PEX is capable of withstanding pressures of up to 145 pounds per square inch. At a maximum operating temperature of 180 degrees Fahrenheit, RHT PEX is limited to a maximum pressure rating of 100 pounds per square inch.

Fluid Capacity

The fluid-carrying capacity of RHT PEX is dictated by the inside diameters discussed above. 1 inch PEX tubing carries approximately .0303 gallons per linear foot, and 3/4 inch PEX tubing has a capacity of .0184 gallons per linear foot on average. RHT PEX tubing with a nominal outside diameter of 5/8 inch carries an average of .0134 gallons per liner foot while the 1/2 inch sized tubing can contain around .0092 gallons per foot. The 3/8 inch pipes hold approximately 0.0050 gallons per linear foot.

Oxygen Barrier

The incorporation of a strong oxygen barrier is critical to protect ferrous connection systems, which would otherwise quickly become subjected to rust and corrosion. With the incorporation of this oxygen barrier, RHT PEX is also made suitable for use carrying potable water.

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