PCS Technical Notes: PT, PTM, Temperature Limitations

Temperature Limitations vs Materials for Plastic Flow Meters

Specified Temperature Limits in the Data Sheet:
Trogamid T (Tubes) --> max: 70'C
Polysulfon (Tubes) --> max: 80'C
PVC (Connections) --> max: 55'C
PP (Connections) --> max: 100'C

About 95% of sales of these type of plastic flow meters are with PVC connections and Trogamid T flow tubes. That means they are for liquids or gases at temperatures less than 55 C. In a small number of cases there is a requirement for a higher temperature but we can not use a plastic flow meter for temperatures above 80 C. This means that 5% of sales are for temperatures between 55 C and 80 C.

For the applications between 55 C and 80 C there are several connections available. There is the PP that is shown in the data sheet but we can also offer coated steel connections (same as standard 6000 series) or SS-316 connections.

In fact, these steel and SS connections are more commonly used than the PP. In the past PP connections were commercially available but they are no longer available and so the factory has to machine them specially when they are required. PP is only normally used when the gas or liquid is corrosive to Steel and SS.

When considering different connection materials it is best to consider the steel and SS connections before the PP connections. We carry the Steel and SS connections for most sizes (not all) in stock in Sydney.

The data sheet shows the that Trogamid T is suitable for 70-80 C but it is not recommend for temperatures above 60 C. The Trogamid T maintains it's strength up to 80 C but for many applications, including water, the tube changes colour (turns milky) when the temperature is above 60 C.

Currently, plastic flow meters are only available in Polysulphon for flow rate sizes from 313-0400 up to 314-2500. The small version PTM is not available in Polysulphon (even though the data sheet shows it).