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Phase III Acid Test Kit


  • Mineral oils
  • Alkylbenzene oils like Zerol
  • EMKARATE RL and Copeland polyol esters
  • Polyvinyl ether (PVE) lubricants


The concentrate of acid in refrigeration oil is expressed as an acid number in mg of KOH per gram of oil (milligrams of potassium hydroxide per gram of oil). The acid number is a measure of the amount of hydroxide solution needed to neutralize the acid in the oil. The more acid there is in the oil, the more potassium hydroxide is needed to neutralize it and, so, the higher the acid number.

In the Phase III test, an acid number of 0.05 mg KOH per gram of oil has been set as the maximum acceptable acid concentration in mineral oil and alkylbenzene oil. In polyol esters, the number is generally accepted as 0.16 mg. Mineral and alkylbenzene oils with an acid number less than 0.05 mg or POE’s with an acid number less than 0.16 mg are acceptable and will cause no change in the color of the test kit’s acid indicator. However, if the respective oils have an acid number greater than these limits, it will cause the acid indicator to change from purple to pink or clear indicating that the oil is contaminated.

Packaging Size Part Number Additional Info
1 box 4320-W8


This product must be used in accordance to the following directions by HVACR professionals only.

The Kit consists of just two bottles which contain the precise amount of solution required to conduct one test. The bottles have screw on caps, eliminating the need to break open glass. To test oil, follow this simple procedure:

  1. Pour the solution from the small bottle into the large bottle. The bottom layer of this mixture will be purple.
  2. Completely fill the small bottle with oil from the unit being tested. Do this immediately after the oil is removed from the crankcase since exposure to air will contaminate the oil and give a false test result.
  3. Pour the oil into the large bottle and shake well.
  4. Wait two to three minutes. A phase separation will develop as the oil rises to the top of the mixture and an aqueous layer forms on the bottom.
  5. If the bottom layer: Stays purple- the oil is satisfactory. Turns Light Pink to Clear- the oil is contaminated.

If the Test indicates that the oil is contaminated, the system should be drained and cleaned, then refilled with the appropriate oil of the proper viscosity.

Product Information:

Literature Downloads

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Product Safety

RTK Information

2611 Schuetz Rd. St. Louis, MO 63043
  • Telephone: 800.554.5499
  • Email: [email protected]
  • Hours: Mon–Fri: 8:00am - 5:00pm (Central Time)

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