Testing Guide

DOWTHERM and DOWFROST heat transfer fluids

The free Fluid Analysis Program is offered to customers currently using DOWTHERM&ttrade; high temperature heat transfer fluids DOWTHERM A, G, J, Q, RP, HT, MX, and SYLTHERM†1 800, XLT, and HF silicone heat transfer fluids.

The purpose of this program is to track the performance of DOWTHERM fluid over time and to minimize unnecessary operational and fluid replacement costs. The analysis includes percent high boilers; percent low boilers; indications of foaming, bumping, or snapping; percent residue; pH of water extract; percent water content.

This simple guide helps you to interpret what each test means and provides a profile of fluid changes over time, which allows you to identify trouble from product contamination or thermal decomposition that may occur in your DOWTHERM or SYLTHERM heat transfer fluid.

Test Test Significance (HTF)
pH Normal range is 5-8. If the fluid sample is outside the expected range of 5-8, this may indicate system contamination with oxygen and/or foreign material; corrosion in the system could result.
"High Boilers" This is a key test for high molecular weight materials that form in a heat transfer system. High boilers above 10% generally warrant fluid replacement. Degradation levels may accelerate when high boilers are more than 15%.
"Low Boilers" Low boilers above 1% should be removed by the customer in a safe and environmentally acceptable way; these products may create excessive pressure, pump cavitation, and poor circulation.
Water, ppm Similar in effect to low boilers; should be removed by the customer in a safe and environmentally acceptable way.
Residue Solid contaminants above 1% may lead to mechanical problems within the heat transfer system, due to erosion of metal surfaces. A common cause is excessive mill scale from piping installed in conjunction with new system construction.

In addition, the customer will be notified as to the suitability of the fluid for continued use in the heat transfer system.

Trademark of Dow Corning Corporation.
1 Dow is a distributor of SYLTHERM products manufactured by Dow Corning Corporation.