PGHD — Heavy-Duty Industrial Propylene Glycol

Sub-Frost PGHD Heat Transfer Fluid is a heavy-duty inhibited propylene glycol formulated for use in closed-loop heat transfer applications. It is ideal for water-based HVAC systems, process heating and cooling, hydronic systems, geothermal applications, and other industrial heat transfer systems requiring reliable freeze, burst, and corrosion protection.

Corrosion and Inhibitor Protection

The advanced inhibitor package in Sub-Frost PGHD provides comprehensive protection for the metals commonly found in heat transfer systems. It helps minimize corrosion, reduces scale and fouling on heat transfer surfaces, and maintains proper pH levels for long-term system performance. Its high-phosphate, multi-component inhibitor technology delivers performance comparable to leading national heat transfer fluid brands.

Sub-Frost PGHD is recommended for operating temperatures from -60°F to 350°F (-51°C to 177°C) and can be formulated to provide the freeze and burst protection required for a wide range of climates and operating conditions.

The inhibitor package provides excellent corrosion protection for steel, cast iron, copper, brass, solder, and aluminum, meeting or exceeding the performance requirements of ASTM D1384, ASTM D8039, and ASTM D8040. It is also compatible with most plastics, elastomers, and rubber components commonly used in heat transfer systems.

Yellow-Metal Protection

Sub-Frost PGHD contains tolyltriazole, an azole-based corrosion inhibitor specifically designed to protect yellow metals such as copper and brass. Tolyltriazole forms a durable molecular barrier on metal surfaces that helps prevent oxidation and corrosion caused by water, oxygen, and elevated operating temperatures. This protection extends the service life of heat exchangers, pumps, valves, and piping while reducing maintenance requirements and preserving system efficiency.

Aluminum System Guidance

Traditional phosphate-inhibited heat transfer fluids, including Sub-Frost PGHD, typically operate within a pH range of 9.0 to 10.7 and provide excellent protection for steel, cast iron, copper, and brass systems. While these fluids are well suited for most HVAC and industrial heating and cooling applications, all-aluminum systems operating above 150°F (65°C) require a different inhibitor technology for optimum protection.

For these applications, Sub-Frost PGAL is recommended. Its organic acid technology (OAT) inhibitor package contains no phosphates, nitrites, amines, or borates and maintains a pH of approximately 8.0 to 8.5 in a 50% solution. Sub-Frost PGAL protects aluminum and other common system metals at operating temperatures up to 350°F (177°C) while remaining compatible with most plastics and elastomers.

Dilution and Availability

Sub-Frost PGHD is available as a full concentrate or can be supplied in virtually any dilution to meet customer requirements. For optimum performance, dilution water should be deionized whenever possible. Low-hardness municipal or well water is generally acceptable, provided hardness does not exceed 170 ppm. Water with excessive hardness may accelerate inhibitor depletion, promote scale formation, and increase the potential for localized corrosion or metal pitting.

To simplify installation and maintenance, Sub-Frost PGHD is available in factory-prepared solutions of 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, as well as 100% concentrate, ensuring the proper glycol concentration for virtually any application.