NB/SH/T 0699-2023 Test method for compatibility between refrigeration oils and refrigerants

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

1. Method number / full name / English name / replacement relationship

• Method number: NB/SH/T 0699—2023
• Chinese full name: Test method for compatibility between refrigeration oils and refrigerants
• English name: Test method for miscibility of refrigerator oils with refrigerants
• Replacement relationship: replaces SH/T 0699—2000 "Test method for compatibility between refrigeration oils and refrigerants"
• Publication/implementation: published on 2023-02-06, implemented on 2023-08-06
• Previous versions: first published in 2000 as SH/T 0699—2000; this is the first revision
• Custodianship: National Technical Committee for Standardization of Petroleum Products and Lubricants, Subcommittee on Petroleum Fuels and Lubricants (SAC/TC280/SC1)
• Drafting organizations: Lubricant Branch of PetroChina Company Limited, Synthetic Grease Branch of Sinopec Lubricant Company Limited
• Main drafters: Li Yanqiu, Wang Peng, Zhang Shoujie, Zeng Yibing, Chen Pengzhen, Liu Hongyu, Meng Meng, Zhang Yitao

2. Scope of application and non-applicability

• This document specifies the test method for compatibility between refrigeration oils and refrigerants (Chapter 1).
• This document applies to refrigeration oils (Chapter 1).
• Method application (Chapter 5): the representative refrigerant is 1,1,1,2-tetrafluoroethane (HFC-134a), and a pressure-resistant glass test tube with a capacity of 100 mL is used as the test tube for compatibility testing; however, it does not limit the use of refrigerants other than those specified in this method or test contents under other capacity conditions.
• When using refrigerants outside the specified ones, the refrigerant characteristics must be confirmed, safety risks assessed, and a safety plan formulated; when using test equipment with capacities outside the specified ones, the total filling amount shall be adjusted according to the oil and refrigerant ratio conditions specified in the method, and the operating pressure of the test equipment shall be confirmed to ensure safety (Chapter 5).
• Non-applicability: no explicit "non-applicability" clause is provided in the available source.

3. Method principle

Place a specified amount of sample and refrigerant into a test tube, raise the temperature at room temperature or in a water bath so that the test oil and refrigerant become a uniform, transparent solution, then cool the test tube in a cooling bath, and measure the temperature at which the solution separates into two phases or the solution as a whole becomes turbid, as the two-phase separation temperature value, to evaluate the compatibility of the refrigeration oil and refrigerant (Chapter 4).

4. Reagents and materials (purity / preparation)

• 6.1 Refrigerant
  • 6.1.1 1,1,1,2-tetrafluoroethane (HFC-134a): industrial grade, conforming to the provisions of GB/T 18826.
  • 6.1.2 Difluoromethane (HFC-32): industrial grade, conforming to the provisions of HG/T 4634.
  • 6.1.3 Chlorodifluoromethane (HCFC-22): industrial grade, conforming to the provisions of GB/T 7373.
• 6.2 Anhydrous ethanol: chemically pure.
• 6.3 Grade 3 water: conforming to the requirements for Grade 3 water in GB/T 6682—2008.
• Preparation method: not provided in the available source.

5. Instruments and equipment

• 7.1 Instruments
  • 7.1.1 Apparatus for compatibility testing of refrigeration oils and refrigerants: the schematic diagram of the apparatus is shown in Figure 1 (reference numbers: 1— test tube; 2— guard plate; 3—T shaped connector; 4— needle valve; 5— safety valve; 6— pressure-resistant hose; 7— cooling bath; 8— thermometer).
  • 7.1.2 Test tube: pressure-resistant glass test tube with a capacity of 100 mL, with a metal fitting having a T shaped connector at the mouth of the test tube; it shall withstand a pressure of 1.96 MPa or less; shape and dimensions are shown in Figure 2.
  • 7.1.3 T shaped connector guard plate: made of stainless steel, with a stainless steel T shaped connector at the upper part and fixed at the lower part with a test tube fixing clip made of polytetrafluoroethylene resin; the T shaped connector is respectively connected to the mouth of the test tube, the needle valve, and the safety valve; shape and dimensions are shown in Figure 3.
  • 7.1.4 Test tube protective cylinder: a cylindrical container made of transparent polypropylene resin with a top cover, capable of containing a test tube (with T shaped connector guard plate) inside; its function is to prevent danger from test tube rupture when heating the test tube after cooling in the cooling bath; shape and dimensions are shown in Figure 4.
  • 7.1.5 Needle valve: made of metal material, structure is detailed in Figure 1.
  • 7.1.6 Safety valve: can be connected to the T shaped connector, working pressure is 1.47 MPa.
  • 7.1.7 Pressure-resistant hose: made of polytetrafluoroethylene resin with composite metal film, maximum pressure is 7.84 MPa.
  • 7.1.8 Cooling bath: a transparent cylindrical Dewar flask that can completely immerse the test tube equipped with the T shaped connector guard plate, the bath liquid uses a suitable liquid cooled by solid carbon dioxide (dry ice), such as ethanol, 2-propanol, etc.; other cooling baths that can ensure the cooling rate and make the temperature at all points in the cooling bath uniform and with suitable capacity may also be used.
  • 7.1.9 Thermometer: typical thermometer requirements are shown in Table 1; other types of temperature measuring devices with the same function may also be used.
• Table 1 Technical specifications for stick-type glass liquid thermometer
  • Scale range/℃: -70～50
  • Total length/mm: 253
  • Immersion/mm: total immersion
  • Diameter/mm: 4.8
  • Graduation/℃: 1
  • Long/mm: 12
  • Long graduation line/℃: 5
  • Bulb diameter/mm: 4
  • Graduation numbers/℃: 10
  • Graduation graduation error/℃: 1
  • Distance from lower end of bulb to -70℃/mm: 81
  • Top shape: ring shape
  • Graduation position distance from lower end of bulb to 50℃/mm: 224
• 7.2 Equipment
  • 7.2.1 Vacuum pump: capable of evacuating to a vacuum degree of 13.3 Pa.
  • 7.2.2 Balance: sensitivity of 0.01 g.
  • 7.2.3 Oven.
  • 7.2.4 Desiccator.
  • 7.2.5 High-pressure-resistant compatibility testing apparatus: used when oil products have high-temperature compatibility testing requirements (such as 54℃～100℃), or when using some refrigerants with higher critical temperatures (such as HFC-32 refrigerant); Figure 5 is a schematic diagram of the high-temperature and high-pressure resistant compatibility testing apparatus, the test tube is a transparent box-type compression-sealed test chamber, composed of three parts: front cover, rear cover, and middle main body; the material of the middle main body withstands a pressure of not less than 6.0 MPa; the upper part of the middle main body is provided with a temperature sensor interface, pressure relief pipeline and safety valve (automatically opens when pressure exceeds 4.5 MPa), sample inlet and vacuum interface, and switch valves are respectively provided on the sample inlet and vacuum pipeline; the three components of the test chamber are all made of quartz glass material treated by pressure-resistant process; the front cover and rear cover are explosion-proof protective plates, each frame is lined with PTFE shock-absorbing sealing gasket; before assembly, the temperature sensor needs to be placed inside the middle main body first, then the front cover, rear cover, middle main body and various connecting pipelines are fixed by stainless steel ferrules and bolt combination (see Figure 5); the test chamber can be directly placed in a cylindrical Dewar flask or in a high-temperature circulating bath for heating and cooling treatment.
  • Figure 5 Reference number description: 1— temperature sensor; 2— safety valve; 3— sample inlet valve; 4— pressure gauge; 5— needle valve; 6— test chamber; 7— oil-agent mixed liquid; 8— high-temperature bath.

6. Recommended operating conditions

• Maximum measurement temperature by test tube method (Table 2):
  • HCFC-22: 38℃
  • HFC-134a: 54℃
  • HFC-32: 19℃
• Maximum measurement temperature by test chamber method (Table 2):
  • HCFC-22: 90℃
  • HFC-134a: 100℃
  • HFC-32: 66℃
• Cooling/heating rate: 1℃/min (10.1.2, 10.2.2).
• The temperature difference between the cooling bath and the solution in the test tube is maintained within 5℃ (10.1.2); the temperature difference between the high-temperature bath and the solution in the test chamber does not exceed 5℃ (10.2.2).
• The pressure in the test tube does not exceed 1.47 MPa (10.1.1); the pressure in the test chamber does not exceed 4.5 MPa (10.2.1).
• The test tube pressure must not exceed 1.96 MPa (8.2); the test chamber pressure must not exceed 6.0 MPa (8.3).
• Safety valve: test tube T shaped connector safety valve working pressure 1.47 MPa (7.1.6, 8.2); test chamber safety valve automatically opens when pressure exceeds 4.5 MPa (7.2.5, 8.3).
• Vacuum degassing: evacuate to about 13.3 Pa (9.3.1.4); evacuate the test chamber system to about 13.3 Pa or less (9.3.2.2).

7. Sampling and sample preparation

• 9.1 Cleaning of test tube: after cleaning the internal dirt of the test tube with detergent, rinse thoroughly with tap water and Grade 3 water in sequence, dry the test tube in an oven, and store in a desiccator for later use.
• 9.2 Weighing of test oil
  • 9.2.1 Weighing of test oil for test tube: accurately weigh 7.50 g±0.10 g of test oil using a balance with a sensitivity of 0.01 g, and inject into the test tube.
  • 9.2.2 Weighing of test oil for high-temperature mutual solubility equipment: place the high-pressure test chamber and the accessories connected to the chamber body (Figure 5) on the balance, open the sample inlet valve, slowly inject 7.50 g±0.10 g of test oil, weigh accurately to 0.01 g and record, then close the sample inlet valve.
• 9.3 Introduction and weighing of refrigerant
  • 9.3.1 Introduction and weighing of refrigerant for test tube equipment
    • 9.3.1.1 Insert a thermometer into the test tube that has been weighed with test oil; connect the test tube to the T shaped connector, and fix the test tube on the guard plate with a test tube fixing clip.
    • 9.3.1.2 After installing the safety valve and needle valve on the T shaped connector guard plate, measure the total mass, accurate to 0.01 g and record.
    • 9.3.1.3 Immerse the test tube equipped with the T shaped joint guard plate into the cooling bath, then use a pressure-resistant hose to connect the needle valve and the refrigerant recovery line (the cooling bath temperature should be maintained below the boiling point of the test refrigerant).
    • 9.3.1.4 Turn on the vacuum pump, and degas the test tube and refrigerant recovery line system to approximately 13.3 Pa.
    • 9.3.1.5 Turn off the vacuum pump, open the main valve of the refrigerant container; introduce refrigerant into the test tube so that the amount of refrigerant slightly exceeds the specified charge, first close the needle valve, then close the main valve of the refrigerant cylinder; disconnect the joint between the needle valve and the pressure-resistant hose, remove the test tube from the cooling bath; wipe the outside of the test tube and the guard plate dry with a dry cloth, place on the balance, adjust the opening of the needle valve so that the weighed amount of refrigerant is accurate to 42.50 g±0.50 g.
  • 9.3.2 Weighing of refrigerant for high-temperature miscibility equipment
    • 9.3.2.1 Immerse the high-pressure test cell containing the test oil into the cooling bath, use a pressure-resistant hose to connect the needle valve with the vacuum pump line and the refrigerant recovery line (the cooling bath temperature should be maintained below the boiling point of the test refrigerant).
    • 9.3.2.2 Sequentially open the needle valve, valve A, valve B and the vacuum pump, and degas the test cell and refrigerant recovery line system to approximately 13.3 Pa or below.
    • 9.3.2.3 Close the vacuum pump and valve B, open the main valve of the refrigerant container (valve C); introduce refrigerant into the test cell so that the amount of refrigerant slightly exceeds the specified charge, first sequentially close the needle valve, valve A and valve C; then disconnect the pressure-resistant hose connection to valve A at the needle valve, remove the test cell from the cooling bath; wipe off the residual coolant on the outside of the test cell with a dry cloth, place the test cell and accessories on the balance, adjust the opening of the sample inlet switch, slowly release the volatile refrigerant gas, so that the weighed amount of refrigerant is accurate to 42.50 g±0.50 g.

8. Analytical procedure

• 10.1 Test tube method test for miscibility of refrigeration oil and refrigerant
  • 10.1.1 Place the test tube containing the test oil and refrigerant into the test tube protective cylinder, cover with the top cap, place at room temperature or heat in a water bath to make the test oil and refrigerant form a uniform, transparent solution; note that the temperature ensures the pressure inside the test tube does not exceed 1.47 MPa; when heated to the maximum temperature specified in Table 2 (test tube method), even if the test oil and refrigerant have not yet formed a uniform, transparent solution, the test must be stopped immediately.
  • 10.1.2 Remove the test tube from the test tube protective cylinder, and perform programmed cooling in the cooling bath at a rate of 1℃/min; at this time, the temperature difference between the cooling bath and the solution in the test tube should be maintained within 5℃.
  • 10.1.3 When a white separate substance appears at the bottom inside the test tube, the solution separates into two phases, or the entire solution becomes slightly turbid, remove the test tube from the cooling bath, wipe the outside of the test tube and the guard plate dry with a dry cloth, then place into the test tube protective cylinder and gently shake to mix evenly.
  • 10.1.4 When the phase separation disappears or the turbidity disappears, the test tube should be returned to the cooling bath, and the operations of clauses 10.1.2 and 10.1.3 should be carried out in sequence.
  • 10.1.5 If the two-phase separation or turbidity still does not disappear even after gently shaking the test tube, the temperature at this time is the two-phase separation temperature of the test oil and refrigerant mixture in the low-temperature region, and the change in the thermometer reading does not exceed 1℃.
• 10.2 Test for high-pressure and high-temperature miscibility of refrigeration oil and refrigerant
  • 10.2.1 Place the high-pressure-resistant miscibility test cell already charged with test oil and refrigerant into a high-temperature bath and heat, so that the test oil and refrigerant form a uniform, transparent solution; note that the temperature ensures the pressure inside the test cell does not exceed 4.5 MPa; when heated to the maximum temperature specified in Table 2 (test cell method), even if the test oil and refrigerant have not yet formed a uniform, transparent solution, the test must be stopped immediately.
  • 10.2.2 Perform programmed heating at a rate of 1℃/min; at this time, the temperature difference between the high-temperature bath and the solution in the test cell shall not exceed 5℃; otherwise, the heating rate should be gradually reduced until the temperature difference between the high-temperature bath and the solution in the test cell is maintained within 5℃.
  • 10.2.3 When a white separate substance appears at the bottom, middle, or upper part inside the test cell, the solution separates into two phases, or suspended droplets appear in the entire solution, or local slight turbidity occurs, remove the test cell from the high-temperature bath, wipe the outside of the test cell dry with a dry cloth, then gently shake to mix evenly.
  • 10.2.4 When the phase separation disappears or the suspended droplets and slight turbidity disappear, the test cell should be returned to the high-temperature bath, and the operations of 10.2.2 and 10.2.3 should be carried out in sequence.
  • 10.2.5 If the two-phase separation or turbidity still does not disappear even after gently shaking the test cell, the temperature of the high-temperature cell at this time is the two-phase separation temperature of the test oil and refrigerant mixture in the high-temperature region, and the change in the thermometer reading does not exceed 1℃.
• 10.3 Test for two-phase separation temperature of test oil and refrigerant mixture
  • 10.3.1 Referring to the operating procedures of clauses 9.2 and 9.3, the weighing work of the test oil and refrigerant mixture can be carried out under any oil content condition [such as 5% (mass)], and the total mass of the test oil and refrigerant mixture is controlled at 50.0 g±0.10 g.
  • 10.3.2 According to the operating provisions of clauses 10.1 to 10.2, complete the two-phase separation temperature test of the test oil and refrigerant mixture under the oil content condition [such as 5% (mass)].
  • 10.3.3 According to testing needs, test oil and refrigerant mixtures with consistent oil content interval conditions (e.g., 5%, 10%, 15%) can be selected as test samples to carry out two-phase separation temperature tests under different oil content conditions, and draw the corresponding two-phase separation curves of the test oil and refrigerant mixtures.

9. Qualitative and quantitative determination and calculation formulas

• 11.1 The temperature measured in clauses 10.1 and 10.2 is the two-phase separation temperature at an oil content of 15% (mass), and the thermometer reading is accurate to 1℃.
• 11.2 Depending on the testing equipment used, when the two-phase separation temperature respectively reaches or exceeds the "maximum measurement temperature" corresponding to the test refrigerant (see Table 2), the test may be terminated; the test result is reported as greater than the "maximum measurement temperature" value corresponding to the testing equipment and refrigerant.
• Calculation formula: not provided in the available source.

10. Precision

• 12.1 Overview: The precision of this document is obtained under the conditions of a test tube capacity of 100 mL, a sample mass fraction of 15%, and a refrigerant HFC-134a mass fraction of 85%, through cyclic testing and statistical calculation; the reliability of test results is judged according to the following provisions (confidence level of 95%).
• 12.2 Repeatability, r: In the same laboratory, the same operator using the same test instrument, the difference between the results of two tests on the same test oil shall not exceed 2℃.
• 12.3 Reproducibility, R: In different laboratories, different operators using different test instruments on the same test oil, the difference between the results of two tests shall not exceed 5℃.
• Note: Reproducibility does not apply to the content of "10.2 Test for high-pressure or high-temperature miscibility of refrigeration oil and refrigerant".

11. Report

• 11.1 The temperature measured in clauses 10.1 and 10.2 is the two-phase separation temperature at an oil content of 15% (mass), and the thermometer reading is accurate to 1℃.
• 11.2 Depending on the testing equipment used, when the two-phase separation temperature respectively reaches or exceeds the "maximum measurement temperature" corresponding to the test refrigerant (see Table 2), the test may be terminated; the test result is reported as greater than the "maximum measurement temperature" value corresponding to the testing equipment and refrigerant.
• Other report format requirements: not provided in the available source.

12. Referenced documents

• GB/T 6682—2008 Water specification and test methods for analytical laboratory
• GB/T 7373 Industrial chlorodifluoromethane (HCFC-22)
• GB/T 18826 Industrial 1,1,1,2- tetrafluoroethane (HFC-134a)
• HG/T 4634 Industrial difluoromethane (HFC-32)
• GB/T 1.1—2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" (mentioned in the foreword, used for the drafting of this document)

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick reference for questions and answers