Fluid Gas Handling

The Love-Hate Relationship Between Hydraulic Hose and Chemical Compatibility

The Love-Hate Relationship Between Hydraulic Hose and Chemical Compatibility - Hydraulic Hoses and Chemical Compatibility - Parker Hose Products DivisionChemical compatibility in regards to hydraulic hose can be complicated, however it is necessary for the performance and hose life. When selecting a hose, you must consider the chemical compatibility of the hose inner tube, cover, fittings and O-rings with the fluid used.

 

Variables affecting resistance of a compound

Some of the variables that affect the resistance of a compound to a chemical attack are: 

  1. Type of media transmitted: Most hydraulic hoses are capable of transporting petroleum oil and liquids with high-water contents, but synthetic oils require dedicated hose materials.
     
  2. Temperature of the media transmitted: Higher temperatures increase the affect of chemicals on compounds. The amount of increase depends upon the polymer and the chemical. A compound quite suitable at room temperature might fail very quickly at higher temperatures. It is important that you do not operate outside hose temperature limits. 
     
  3. Service conditions: A rubber compound usually swells when exposed to a chemical. Within a given percent of swell, a hose tube may function satisfactorily if the hose is in a static condition, but may fail quickly if the hose is subject to flexing. 
     
  4. Grade or blend of the rubber compound: Basic polymers are sometimes mixed or blended to enhance a particular property for a specific type of application.

 

Below is a generic overview of how some polymers can react with different chemicals or environmental factors, however there are many factors that might change the compatibility outcome:

 

Chemical / Environmental Factor Chloroprene Nitrile Butyl EPDM CPE
Flame Resistance Very Good Poor Poor Poor  Good
Petroleum Base Oils Good Excellent Poor Poor Very Good
Diesel Fuel Good to Excellent Excellent Poor  Poor  Very Good
Gas Permeation Good Good Outstanding  Fair to Good Good
Weather Good to Excellent Poor Excellent Excellent Good
Ozone Good to Excellent Poor Excellent Outstanding Good
High Temperature Good Good Good Excellent Excellent
Low Temperature Fair to Good Poor to Fair  Very Good Good to Excellent Good
Water-Oil Emulsions Excellent Excellent Good Poor Excellent
Water-Glycol Emulsions Excellent Excellent Excellent Excellent Excellent
Diesters Poor  Poor  Excellent Excellent Very Good

 

Extra caution required

Exercise additional caution when selecting a hydraulic hose for gaseous applications subject to permeation. Some fluids that raise concerns include:

  • Liquid and gas fuels
  • Refrigerants
  • Helium
  • Fuel oil
  • Natural gas

If gas permeates through the tube, consider pin-perforated covers to prevent gas build-up. Don’t neglect the potentially hazardous effects of permeation, such as explosions, fires, and toxicity. Refer to applicable standards for specific precautions involving fuels and refrigerants. For instance, Parker has engineered hoses for the transportation and refrigeration market that are specifically designed for these applications:

  • Diesel fuels and antifreeze (Parker’s 213, 266, 201, 206, 611HT and 221FR hydraulic hoses)
  • Compressed natural gas (Parker’s SS23CG hose),
  • Liquefied petroleum gas (Parker’s SS23CG and SS25UL hydraulic hoses)
  • Refrigerant (Parker’s 285 and 244 hose) 

Hydraulic Hose and The Love-Hate Relationship Between Hydraulic Hose and Chemical Compatibility - Chemical Compatibility - Parker Phosphate Ester Fluid Compatible HosesPhosphate ester is another chemical that needs distinct design elements. Nitrile or rubber is fantastic for petroleum-based hydraulic oil, but would not be compatible with a synthetic fluid such as phosphate ester, which requires EPDM. Special attention should also be paid to chemical compatibility of the outer cover as well. That is why Parker offers a line of phosphate-ester fluid compatible hoses that feature inner tubes and outer covers that resist aggressive aircraft hydraulic fluids.


When in doubt, ask the manufacturer

Each manufacturer should have a document regarding chemical resistance for each of the hydraulic hose and fittings they manufacture. Usually, the basis for the ratings includes actual service experience, the advice of various polymer suppliers, and the considered opinion of chemists. When in doubt, a sample of the compound should always be tested with the particular chemical it is to handle. Click here to reference Parker’s media guidelines in regards to chemical resistance.   

 

The Love-Hate Relationship Between Hydraulic Hose and Chemical Compatibility -Kyri McDonough, Hose Products Division, Parker HannifinArticle contributed by Kyri McDonough, marketing services manager at Hose Products Division, Parker Hannifin.

 

 

 

 

Other related topics on hydraulic hose, hose application, and selection criteria:

Decoding a Hydraulic Hose Layline
Five Most Important Factors You Need to Consider for Hydraulic Fittings
Hydraulic Hose 101: Fast Facts
Top 8 Reasons Hydraulic Hoses Fail
Top 5 Reasons Customers Choose GlobalCore Hose
Successful Hydraulic Hose Assembly Starts Here

 
Categories
Recent Posts by Author

Extreme Temperatures Are No Issue for Parker's Patented Metal Seal for ORFS Fittings

The tiniest equipment components are as critical as those a thousand times their size. Particularly under extreme conditions, every link in the chain, big or small, is on trial.  The fluid conveyance...

The Importance of Natural Gas Product Certifications

To stay at the forefront of the competitive transportation markets, fleet managers are turning to alternative fuels that meet the environmental and economic needs of today and in the future.  Natural...

The Love-Hate Relationship Between Hydraulic Hose and Chemical Compatibility

Chemical compatibility in regards to hydraulic hose can be complicated, however it is necessary for the performance and hose life. When selecting a hose, you must consider the chemical compatibility...
Comments

Comments for The Love-Hate Relationship Between Hydraulic Hose and Chemical Compatibility


Please note that, in an effort to combat spam, comments with hyperlinks will not be published.

Leave a comment





Captcha