Already a subscriber?
MADCAD.com Free Trial
Sign up for a 3 day free trial to explore the MADCAD.com interface, PLUS access the
2009 International Building Code to see how it all works.
If you like to setup a quick demo, let us know at support@madcad.com
or +1 800.798.9296 and we will be happy to schedule a webinar for you.
Security check
Please login to your personal account to use this feature.
Please login to your authorized staff account to use this feature.
Are you sure you want to empty the cart?
ASHRAE Standard 97 Sealed Glass Tube Method to Test the Chemical Stability of Materials for Use within Refrigerant Systems (ANSI/ASHRAE Approved) , 2007
- FOREWORD
- 1. PURPOSE
- 2. SCOPE
- 2.1 This standard describes the preparation of sealed glass tubes and the procedure for charging them with refrigerant, lubricant, other materials to be tested, or combinations of these.
- 2.2 A procedure for aging the tubes, usually at elevated temperatures, is described. The tubes are evaluated by quantitative or ...
- 2.3 The technique described may be used for evaluating many different types of materials. Therefore, the standard does not descr...
- 2.4 Detailed safety precautions are included in Section 8, “Safety Requirements.”
- 3. APPARATUS
- 3.1 A sealed glass tube generally consists of a borosilicate glass tube 9 mm (0.35 in.) OD ° 7 mm (0.27 in.) ID ° approximately ...
- 3.2 The tube charging apparatus is illustrated in Figure 1. This apparatus consists of a manifold (metal or glass), vacuum pump,...
- 3.3 An aluminum block is used for aging the sealed glass tubes at elevated temperatures. The aluminum block has cylindrical hole...
- 3.4 Individual pipe chambers may be more convenient for testing a small number of samples, instead of the aluminum block described above. These individual chambers may be constructed of metal pipe and closed at both ends with threaded caps.
- 3.5 The electrically heated aging oven shall have mechanical convection capable of maintaining a uniform temperature with ±1.0ËšC...
- 3.6 The tube opening apparatus is illustrated in Figure 3. This apparatus is suitable for safely and conveniently opening a sealed tube for subsequent analysis of the contents. An alternative apparatus is illustrated in Figure 4.
- 3.7 Flexible tubing (PVC or rubber) is often used in preparation of sealed glass tubes. It is important to clean the tubing prior to use. It must be free of excess plasticizer, lubricants, powders, and other contaminants.
- 4. PROCEDURE FOR PREPARING THE SEALED GLASS TUBES
- 4.1 Preparation of the Glass Tube
- 4.2 Preparation of Materials
- 4.3 Adding Materials to Tubes
- 4.4 Adding Refrigerant to the Tubes
- 4.5 Sealing the Tubes
- 4.6 Alternative Filling Methods
- 4.7 Inspection of Tubes
- 4.8 Testing in Metal Vessels. Frequently, it is necessary to test materials that cannot be inserted in glass tubes because of si...
- 5. AGING THE SEALED GLASS TUBES
- 5.1 Aging Times and Temperatures. The temperature and time chosen for aging shall be selected by the experimenter according to t...
- 5.2 Inspection During Aging. It may be desirable to inspect the tubes visually and record observations at several time intervals...
- 5.3 Aging Tubes with Equalized Pressure. In some circumstances, the pressure achieved in the sealed tubes at aging temperature e...
- 6. ANALYSIS OF THE TUBES
- 6.1 The exact method of analysis shall be chosen by the experimenter according to the intended purpose. Analytical methods that ...
- 6.2 A visual inspection has been used in the past. Both the liquid phase and the metal test pieces in the tubes are examined, and the appearance of the tubes is compared with controls containing materials of known stability.
- 6.3 Opening Tubes for Gas Analysis
- 6.4 Reference Analysis Methods
- 7. SIGNIFICANCE OF RESULTS
- 7.1 The sealed tube test procedure has long been used to evaluate and select materials for use in refrigeration systems.10 Data ...
- 7.2 It is recommended that the following information be included when reporting results: aging time and temperature, identificat...
- 7.3 This method is not a specification with pass/fail criteria. It is used for preparing, aging, and analyzing sealed tubes to obtain test results for such specifications. It is left to the interested parties to establish pass/fail criteria of results.
- 8. SAFETY REQUIREMENTS
- 8.1 There are hazards in handling sealed glass tubes and the materials being tested. At times the absolute pressure inside the t...
- 8.2 The operator shall stand behind a large safety shield made of safety glass or plastic whenever examining a sealed glass tube...
- 8.3 Protective gloves shall be worn when handling the hot or frozen tubes during and after sealing.
- 8.4 Solvents used in this method are highly flammable. Provide adequate ventilation; wear proper gloves (e.g., neoprene, nitrile); avoid sparks, flame, or heat. Know the location of the nearest fire extinguisher, and take appropriate fire precautions.
- 8.5 When using the glass charging system, adequate safeguards must be taken to avoid excessive pressure on the glass system that...
- 8.6 When sealing a glass tube with an oxygen-gas torch, protect the eyes from the yellow flare in the gas flame by using dark glasses (e.g., didymium).
- 8.7 Several safety considerations are required for handling refrigerants under pressure. The operator shall be thoroughly famili...
- 8.8 Liquid nitrogen in a Dewar flask is used for cooling the sealed glass tube to load it with refrigerant and for a subsequent ...
- 8.9 Carbon dioxide (CO2) is classified as a nonflammable high-pressure liquid and gas asphyxiant. Skin exposure may cause a burn...
- 8.10 Ammonia (NH3) is a colorless gas that is a severe eye, skin, and respiratory irritant; therefore, adequate ventilation and ...
- 8.11 Refer to the Material Safety Data Sheet for any materials used in this method for additional safety information.
- 8.12 Tubes that have some imperfection are more likely to explode the first time they are heated or even while they are warming ...
- 8.13 During analysis, after a tube is frozen in the liquid nitrogen, the “refrigerant” pressure is no longer present. However, i...
- 9. REFERENCES
- Informative APPENDIX A- Calculation of Refrigerant Pressure In Sealed Tubes Containing 0.7 ml of Refrigerant
- A1. Calculation of Refrigerant Pressure in Sealed Tubes Containing 0.7 mL of Refrigerant
- A2. Calibration of Manifold Volume
- A2.1 Place a rubber stopper in the mouth of a 500 mL suction flask, then completely fill it with water through its side arm by means of a burette. This will yield a satisfactory value for the volume of the suction flask (V1).
- A2.2 Drain the water and dry the flask. Connect the side arm to the manifold at one of the filling ports by means of a short len...
- A2.3 Evacuate the manifold, but not the flask, to 13 Pa (100 millitorr) or less. Close the valve between the refrigerant trap and the manifold.
- A2.4 Measure and record as P1 the barometric pressure at the time and site of the equipment. This is the pressure in the suction flask.
- A2.5 Slowly open the valve to the suction flask and record the final pressure P2. Calculate volume of manifold as V in the following example, shown with both inch-pound and SI units.
- A3. Calculation for Refrigerant Charging by Change in Manifold Pressure
- A3.1 Inch-Pound Units
- A3.2 SI Units
- Informative APPENDIX b- BIBLIOGRAPHY [Go to Page]