1、ANSI/ASHRAE Standard 35-2014(Supersedes ANSI/ASHRAE Standard 35-2010)Method of TestingDesiccants forRefrigerant DryingApproved by the ASHRAE Standards Committee on January 18, 2014; by the ASHRAE Board of Directors on January 22, 2014;and by the American National Standards Institute on January 23, 2
2、014.ASHRAE Standards are scheduled to be updated on a five-year cycle; the date following the standard number is the year ofASHRAE Board of Directors approval. The latest edition of an ASHRAE Standard may be purchased on the ASHRAE website(www.ashrae.org) or from ASHRAE Customer Service, 1791 Tullie
3、 Circle, NE, Atlanta, GA 30329-2305. E-mail:ordersashrae.org. Fax: 678-539-2129. Telephone: 404-636-8400 (worldwide) or toll free 1-800-527-4723 (for orders in US andCanada). For reprint permission, go to www.ashrae.org/permissions. 2014 ASHRAE ISSN 1041-2336SPECIAL NOTEThis American National Standa
4、rd (ANS) is a national voluntary consensus standard developed under the auspices of ASHRAE.Consensus is defined by the American National Standards Institute (ANSI), of which ASHRAE is a member and which has approved thisstandard as an ANS, as “substantial agreement reached by directly and materially
5、 affected interest categories. This signifies the concurrenceof more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that aneffort be made toward their resolution.” Compliance with this standard is voluntary until and unless
6、a legal jurisdiction makes compliancemandatory through legislation.ASHRAE obtains consensus through participation of its national and international members, associated societies, and public review.ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing
7、the Standard. The ProjectCommittee Chair and Vice-Chair must be members of ASHRAE; while other committee members may or may not be ASHRAE members, allmust be technically qualified in the subject area of the Standard. Every effort is made to balance the concerned interests on all ProjectCommittees.Th
8、e Manager of Standards of ASHRAE should be contacted for:a. interpretation of the contents of this Standard,b. participation in the next review of the Standard,c. offering constructive criticism for improving the Standard, ord. permission to reprint portions of the Standard.DISCLAIMERASHRAE uses its
9、 best efforts to promulgate Standards and Guidelines for the benefit of the public in light of available information andaccepted industry practices. However, ASHRAE does not guarantee, certify, or assure the safety or performance of any products, components,or systems tested, installed, or operated
10、in accordance with ASHRAEs Standards or Guidelines or that any tests conducted under itsStandards or Guidelines will be nonhazardous or free from risk.ASHRAE INDUSTRIAL ADVERTISING POLICY ON STANDARDSASHRAE Standards and Guidelines are established to assist industry and the public by offering a unif
11、orm method of testing for ratingpurposes,bysuggestingsafepracticesindesigningandinstallingequipment,byprovidingproperdefinitionsofthisequipment,andbyprovidingother information that may serve to guide the industry.The creation of ASHRAE Standards and Guidelines is determined by the need for them,and
12、conformance to them is completely voluntary.In referring to this Standard or Guideline and in marking of equipment and in advertising, no claim shall be made, either stated or implied,that the product has been approved by ASHRAE.ASHRAE Standard Project Committee 35CognizantTC:TC 3.3, Refrigerant Con
13、taminant ControlSPLS Liaison: Kenneth W. CooperAlan P. Cohen, Chair* Danny HalelJay E. Field, Secretary* Robert W. Woods*Douglas G. Gildehaus* Robert W. Yost*Denotes members of voting status when the document was approved for publicationASHRAE STANDARDS COMMITTEE 20132014William F. Walter, Chair Dav
14、id R. Conover Malcolm D. KnightRichard L. Hall, Vice-Chair John F. Dunlap Rick A. LarsonKarim Amrane James W. Earley, Jr. Mark P. ModeraJoseph R. Anderson Steven J. Emmerich Cyrus H. NasseriJames Dale Aswegan Julie M. Ferguson Janice C. PetersonCharles S. Barnaby Krishnan Gowri Heather L. PlattSteve
15、n F. Bruning Cecily M. Grzywacz Douglas T. ReindlJohn A. Clark Rita M. Harrold Julia A. Keen, BOD ExOWaller S. Clements Adam W. Hinge Thomas E. Werkema, Jr., CODebra H. KennoyStephanie C. Reiniche, Manager of Standards ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribu
16、tion, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.CONTENTSANSI/ASHRAE Standard 35-2014,Method ofTesting Desiccants for Refrigerant DryingSECTION PAGEForeword. 21 Purpose 22 Scope . 23 Definitions. 24 Classification 25 Apparatus . 26 Prepa
17、ration and Analysis 37 Test Procedure. 38 Proof of Equilibrium: Chemical Reaction 49 Data to be Recorded 410 Normative References 4Informative Annex A: Bibliography4NOTEApproved addenda, errata, or interpretations for this standard can be downloaded free of charge from the ASHRAEWeb site at www.ashr
18、ae.org/technology. 2014 ASHRAE1791 Tullie Circle NE Atlanta, GA 30329 www.ashrae.org All rights reserved.ASHRAE is a registered trademark of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.ANSI is a registered trademark of the American National Standards Institute.
19、 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.2 ANSI/ASHRAE Standard 35-2014(This foreword is not part of this standard. It is merelyinformative and doe
20、s not contain requirements necessaryfor conformance to the standard. It has not beenprocessed according to the ANSI requirements for astandard and may contain material that has not beensubject to public review or a consensus process.Unresolved objectors on informative material are notoffered the rig
21、ht to appeal at ASHRAE or ANSI.)FOREWORDFirst published in 1976, ASHRAE Standard 35 was reaf-firmed in 1983 and revised in 1992 and again in 2010.The2010 version included a change to use the Karl Fischer cou-lometric titrator, a commonly used laboratory instrument,which simplified the test and provi
22、des more accurate resultsthan the previous test method.This current 2014 revision to Standard 35 includesupdated references and minor editorial changes. The stan-dard was prepared under the auspices of ASHRAE. It may beused, in whole or in part, by an association or governmentagency with due credit
23、to ASHRAE. Adherence is strictly ona voluntary basis and merely in the interest of obtaining uni-form standards throughout the industry.1. PURPOSEThis standard establishes a method of testing desiccantsfor use in refrigerant drying.2. SCOPE2.1 This standard provides a method of testing desiccantsonl
24、y. For testing and rating driers that use these desiccants,refer to ANSI/ASHRAE Standard 63.1, Method of TestingLiquid Line Refrigerant Driers (see Informative Annex ABibliography).2.2 The principle of this standard is to keep a desiccant ofknown water content in contact with the desired refrigerant
25、until equilibrium has been established under known tempera-ture conditions, after which the water content of the refriger-ant is determined.2.3 This standard is applicable to all desiccants that do notreact with the desired refrigerant.3. DEFINITIONSFor the purposes of this standard, the following t
26、erms anddefinitions apply.desiccant: a solid that will collect and hold water and is insol-uble in the refrigerant medium used.equilibrium-point dryness (EPD): the water content of aliquid refrigerant after being in contact with a specific desic-cant at a particular temperature long enough to reach
27、an equi-librium state. Equilibrium-point dryness (EPD) is expressedas milligrams of water per kilogram of refrigerant (parts permillion ppm).water capacity: the amount of water collected and held by thedesiccant while maintaining a specified EPD in the liquidrefrigerant passing through it at a certa
28、in liquid-refrigeranttemperature. Water capacity is measured in parts of water per100 parts of desiccant by weight activated in accordance withthe manufacturers instructions.4. CLASSIFICATION4.1 This method of test is concerned with testing desiccants,specifically with determining the water capacity
29、 of a desic-cant and the water concentration of a refrigerant when theyare in equilibrium.4.2 Since this standard is concerned only with equilibriumconditions at a given temperature, no consideration is given tothe effect of the design of the container holding the desiccant.Note: In ASHRAE Standard
30、63.1, the method of testingdiscussed here, with certain modifications, is used to test thedesiccant contained in a completed drier unit to determine itswater capacity when in equilibrium with the refrigerantcontaining a given amount of water. (See InformativeAnnex ABibliography.)4.3 This method of t
31、esting desiccants uses liquid refrigerantin equilibrium with the desiccant.4.4 The rate of drying is not considered in this standard.Measurements are made under conditions ensuring practicalequilibrium.4.5 Physical characteristics of the desiccant such as particlesize, dusting properties, hardness,
32、and the form of desiccant(i.e., molded or granular) are not considered in this standard.5. APPARATUSThe following apparatus is required for the method oftesting in this standard.5.1 A constant-temperature bath or cabinet that is able tomaintain a given temperature with an accuracy of 1C(2F) and is c
33、apable of being set at any temperature withinthe range of desiccant use. The equilibration vessel may beplaced inside a constant-temperature cabinet.5.2 An analytical balance having a sensitivity of 0.0001 g(2107lb).5.3 A pan-type balance having a sensitivity of 0.01 g(2105lb) and a capacity of 5000
34、 g (11 lb).5.4 A stainless-steel equilibration vessel with minimumcapacity of 300 mL (10 oz).This vessel shall have a maximumworking pressure in excess of the anticipated test pressure.The vessel with its associated valve shall be adequately leaktested and dried prior to performing the test.5.5 A Ka
35、rl Fischer coulometric titrator. As specified in thetitrator instructions, a flowmeter and a 3A molecular sievedrier may be used.Also, a heat source (e.g., a heat gun), a tem-perature-monitoring device (for equilibration temperaturesabove room temperature), and a vacuum pump with a microngauge are r
36、equired.Note: The automatic concentration calculation feature ofthe Karl Fischer coulometric titrator may be used. ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written per
37、mission.ANSI/ASHRAE Standard 35-2014 35.6 Additional apparatus and reagents as required by themethod ofAHRI Standard 700-2006,Appendix C (2008 revi-sion), Part 2.15.7 Crucibles with lids (platinum, fused silica, or porcelain)of sufficient volume to contain 10 g (0.022 lb) of the desiccantbeing teste
38、d.5.8 A constant-temperature oven capable of maintaining thedesiccant activation temperature specified by the desiccantmanufacturer within 10C (20F).6. PREPARATION AND ANALYSIS6.1 Preparation of DesiccantsThe desiccant shall be prepared as follows.6.1.1 In this test procedure, desiccant shall be par
39、tiallyhydrated by adding water as vapor to the activated desiccantand then accurately determining the amount added. The per-formance of the desiccant shall be calculated from a measure-ment of the water content of the refrigerant at equilibriumwith the desiccant containing a predetermined quantity o
40、fwater.6.1.2 The desiccant shall be adjusted to approximately thedesired water content by weighing the required amount ofdesiccant on the pan-type balance (see Section 5.3), spreadingit in a mono-particle layer, and exposing it to a damp atmo-sphere. Usually the laboratory atmosphere is sufficiently
41、damp to obtain the desired water content, although care mustbe exercised so that acid or other chemical vapors are notadsorbed by the desiccant.6.1.3 Periodically weigh the desiccant to determine whenthe desired water content has been attained.A fan can be usedto circulate the air and increase the r
42、ate of adsorption.6.1.4 Transfer the partially hydrated desiccant to a taredequilibration vessel (see Section 5.4) and weigh it. Hold theequilibration vessel at 77C (170F) for 24 hours in order toensure uniform distribution of the water. If desired, a closed-loop air system can be used under the sam
43、e conditions. Coolthe equilibration vessel containing the partially hydrated des-iccant to room temperature. The precise water content isdetermined by the method in Section 6.2.6.2 Analysis: Determination of Water Content ofDesiccantsWater content of the prepared desiccant shall be deter-mined as fo
44、llows.6.2.1 Weigh duplicate samples of approximately 10 g(0.022 lb) of the partially hydrated desiccant on the analyticalbalance in tared porcelain crucibles. Cover each crucible toavoid the loss or gain of water during the weighing process.6.2.2 After weighing, the uncovered crucibles with theconta
45、ined samples shall be heated in a constant-temperatureoven at the temperature and for the time specified by the man-ufacturer as necessary to activate the desiccant.6.2.3 After the crucibles and contents have been exposedto activating conditions for the required time, they shall becooled in a closed
46、, dried container and weighed. The loss inweight shall be recorded as parts of water per 100 parts of acti-vated desiccant by weight. This resulting percentage of waterin the desiccant represents the water capacity of the desiccantat the resulting EPDs and temperatures determined under theprocedures
47、 outlined in the test procedure in Section 7.6.2.4 For purposes of this standard, the water content isconsidered to be zero when the desiccant is activated in accor-dance with the manufacturers instructions.Note: Activation of a desiccant should not be confusedwith the widely used test called loss o
48、n ignition (LOI), inwhich a desiccant is heated to temperatures far above its safeactivation temperature and the resulting weight loss is deter-mined. This LOI test removes both chemically bound andadsorbedwaterfromthedesiccantandresultsindestructionofthe desiccant. The test is used to determine tot
49、al water andvolatile content in a desiccant as a quick quality control test.However, it is never used to determine the usable water capac-ity of a desiccant, which is the intent of this standard.Note: Activation of a desiccant is conducted at a temper-ature that removes adsorbed water but does not remove chem-ically bound water. Thus the desiccant is not harmed byactivation. The activation time and temperature varies fordifferent desiccants and therefore must be specified by themanufacturer.6.2.5 If duplicate results differ by more than 0.2 parts p
