standard

Oil separation standards

November 13, 2025
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Oil separators play a crucial role in many industries. From wastewater treatment plants to the petrochemical, steel, and food industries, these devices contribute to environmental protection and optimize industrial processes by separating oil and water. But how can you     ensure the quality and performance of your separators?     The answer lies in      complying with the relevant standards.

This article analyzes      international and national standards for oil separators     ,      criteria for selecting equipment that meets industry requirements      ,      and testing methods for ensuring conformity      . This comprehensive guide will help you choose the optimal equipment for your application and  ensure  optimal performance.

Chapter 1: Introduction to the basic parameters  of oil separation

1-1. International Standards

a) ISO 9001 (Quality Management System)

This standard ensures that manufacturers of oil separators adhere to strict   quality control procedures  . ISO 9001-certified equipment is approved with regard to its materials, construction, and installation.

b) ISO 14001 (environmental management)

Since skimmers are directly related to  preventing  water pollution, this standard demonstrates the manufacturers’ commitment to minimizing negative environmental impacts.

c) API 421 (American Petroleum Institute standard)

This scale was specifically developed for oil/water separation plants in the oil and gas industry and defines technical characteristics such as separation efficiency, material type and chemical resistance.

1-2. American Standards (ASTM and OSHA)

  • ASTM D3921   : Test method     for the performance of oil separators

  • OSHA 1910.146     : Safety requirements for the prevention of fires and explosions in oily environments

1-3. European Standards (EN and CE)

  • EN 858     : Specification for oil-water separation

  • CE marking     : Safety certification for devices used in the European Union.

1-4.      Iranian national   standards (ISIRI and Ministry of Environment)

  • ISIRI Standard 1-4567     : General requirements for oil separators

  • Guidelines of the Iranian Environmental Protection Agency (EPA)     : Permissible level of petroleum products in industrial wastewater (less than 5 ppm)

Chapter Two: Criteria for selecting an oil separator according to standards

2-1. Types of oils and liquids

  • Light oils (such as gasoline and kerosene)     : Requires an oil separator     with a polyurethane belt.

  • Heavy fuel oil (diesel fuel, motor oil)     : Use a stainless steel container.

  • Water-in-oil emulsions     : Modern systems with centrifugal mechanisms are    required.

2-2. Performance and consumption

  • API 421   defines       the minimum required flow capacity depending on the inflow velocity.

  • Example: With a flow rate of 10 cubic meters per hour, the minimum separation capacity should be 2 liters of oil per hour.

2-3. Materials of the parts that come into contact with oil

material chemical resistance Relevant standards
316 stainless steel Resistant to acids and salts. ASTM A240
Polyurethan Corrosion-resistant ISO 4649
Teflon chemical resistance FDA 21 CFR

2-4. Environmental conditions

  • Operating temperature (the standard  EN 858      recommends    a range of -20 to +60 degrees Celsius)

  • Acidic or alkaline environments (according to      NACE MR0175     )

Chapter Three: Standard Tests for Oil Separation

3-1. Classification efficiency test (according to ASTM D3921)

  1. Sample preparation     :    Mixture    of oil and water in specific concentrations.

  2. Perform the test     : Place a sample into the device and measure the remaining oil.

  3. Efficiency calculation     : It should be above 95%.

3-2. Durability test (according to ISO 9001 standard)

  • 5000 hours of continuous operation   under      industrial conditions

  • Checking the parts for corrosion      after testing.

3-3. Security check (according to OSHA standards)

  • Spark protection      (for potentially explosive atmospheres)

  • Emergency stop system

3.4. Verification of compliance with environmental standards

  • Analysis of the discharged wastewater      (oil content below 5 ppm according to Iranian standards)

Chapter Four: Standards-Based Implementation and Maintenance Methods

4-1. Correct Installation

  • Maintain a certain distance from the    wall  (at least 50 cm).

  • The devices were configured (according to the manufacturer’s instructions).

4-2. Regular maintenance

  • Daily     : Check the amount of oil collected.

  • Monthly     : Clean belt or pulley.

  • Annually     : Replacement of bearings and washers.

4-3. Documentation

  • The results of the regular inspections must be documented (in accordance with the requirements of ISO 9001).

  • Maintenance    and repair reports  

In conclusion

Selecting the right oil separator is only possible with strict adherence to technical and environmental standards     . Since these standards vary depending on the industry, the following is important:

  1. Determine your requirements based on the type of oil and the flow rate.

  2. Choose devices with international certification (e.g., ISO,      API      , EN).

  3. Regular inspections are carried out in accordance with applicable standards.

✅ It is recommended to consult an experienced specialist to select the best equipment.