Like Oil and Water, and Ethylbenzene?

Chemical Resistance Compatibility

Tips From the Service Bench

Technology TIP

When pumping liquids, you must be sure flow path wetted materials are compatible with intended media. If not researched and tested, issues may arise in the field that may impact product life and maintenance schedules.

While Chemical Compatibility Charts are a good place to start your research, there is typically a standard disclaimer at the bottom that limits their application and places the responsibility on you the buyer, such as:

Warning: The information in this chart is to be used as a guide, ONLY. Although believed to be accurate, actual decisions on material selection need to be thoroughly tested and evaluated by the customer for each specific application. It is the full responsibility of the customer to perform and evaluate the compatibility of materials for their specific requirements. The manufacturer takes no responsibility, etc., etc…


ARE WE COMPATIBLE?

Polymer components exposed to incompatible media can experience swelling or loss of physical properties. When severe, these effects can lead to degradation of pump performance, reduced pump life, leakage, and even pump failure. These issues are avoided with proper material selection. Many pump manufacturers provide a selection of flow path materials to meet most needs, and some provide additional material options for exceptional cases.

TESTING OUR RELATIONSHIP

So, how do you go about testing chemical compatibility? You can get test swatches of possible polymer materials. But, results using test swatches can be less than applicable since they may be much thinner or thicker than the actual parts used in pumps. KNF offers a better way to assist your compatibility decisions, with our Chemical Resistance Test Kit (p/n 173610). This kit contains our most popular head plates and elastomer valves materials. These are actual production parts in current use, so they offer the best test subjects possible. For each material, two parts are supplied – one for resistance testing, the other as a comparison reference. Simple instructions will guide you through the static soak test process.

Chemical Resistance Kit Materials

Kit materials: (1) PEEK (2) PPS (3) PVDF (4) PP (5) FFKM-A (6) FKM (7) EPDM (8) FFKM-B (9) FFKM-C

SUMMARY

In a typical fluidic system, component lifetime will be influenced by several variables beyond simple compatibility of the liquid media, including chemical concentration, liquid temperature, operating pressure, flow rate, and exposure to abrasive materials. A static soak test cannot, therefore, replace a long-term validation test with a pump running in a real system under system parameters. But, a static soak test is well suited as part of an initial screening to identify and eliminate materials which are clearly incompatible with expected liquids.

Contact KNF today for a Chemical Resistant Test Kit and get pumping with confidence!

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Safe, Gas-tight Transfer of Dangerous and/or Expensive Media

The following is a case study presenting the issues encountered and overcome when problem-solving a pyrophoric gas transfer application with KNF customer, Air Products and Chemicals.

INTRODUCTION

Spontaneously-Combustible-SignAir Products is a leading international manufacturer of industrial gases and chemicals. With a staff of over 21,000, the company, based in Pennsylvania, operates in 50 countries across the globe and supplies a wide variety of processing media for myriad applications and industries.

Among goods produced specifically for the semiconductor and solar industry, Air Products manufactures a special gas mixture employed in etching and gas deposition processes to coat silicon wafers and glass substrates; these methods help, for example, to create the active films in flat panel displays and solar cells.

Owing to their pyrophoric properties, the utmost care is required both when manufacturing and using these gases. All system components that store or transfer the gases must therefore prevent air contamination. Should such gases come into contact with air, an exothermic reaction takes place in which a telltale oxidation product is created and deposited in the form of a white coating.

>> Read the Complete Case Study

Obtaining Optimal Process Pump Performance

KNF process pumps for hazardous media and environments

KNF N 860.3 FTI Ex – for pyrophoric gas application

In the latest edition of Processing magazine, KNF Process Pump Engineer, Rich Aerts highlights the importance of adapting a diaphragm pump to its operating conditions, media properties, and the needs of the process itself. The article includes a real-life example of pump materials being modified to achieve optimal performance, and illustrates the importance of gas-tightness in the manufacturing of pyrophoric processing gases.

Read article: “Transferring Pyrophoric Processing Media with Safety” (Processing, Sep. 2015) >>