i) All Members of Division Council ii) All Members of Refrigeration & Air Conditioning Sectional Committee, ME 03 iii) Others interested

Transcription

1 DRAFT IN WIDE CIRCULATION Our Ref. Date ME 03 /T-11 28/ Technical Committee: _ME 03 i) All Members of Division Council ii) All Members of Refrigeration & Air Conditioning Sectional Committee, ME 03 iii) Others interested Dear Sir(s), Please find enclosed the following document: Doc: ME 03(0875)C Draft Indian Standard Specification for walk-in cold rooms (ICS ). Kindly examine the draft standard(s) and forward your views, stating any difficulties which you are likely to experience in your business or profession, if this/these is/are finally adopted as National Standard(s). Last date for comments: Comments, if any, may please be made in the format as given overleaf and mailed to the undersigned at the above address. Communication through is solicited at In case no comments are received or comments received are of editorial nature, you will kindly permit us to presume your approval for the above document as finalized. However, in case of comments of technical in nature are received then it may be finalized either in consultation with the Chairman, Sectional Committee or referred to the Sectional committee for further necessary action if so desired by the Chairman, Sectional Committee. The document is also hosted on BIS website Thanking you, Yours faithfully Encl.: As above. (C.K. VEDA) Scientist F & Head (MED)

2

3 FOREWORD 0.1 Formal clauses will be added late. 0.2 This standard was first published in The refrigeration and air conditioning industry, both in India and abroad, has made tremendous strides since then. Walk-in type Cold Rooms have undergone a quantum improvement with the introduction of rooms assembled with pre-fabricated rigid Polyurethane foam insulated panels, installed with factory made cooling systems. These are now manufactured within the country. Hence it was decided to revise this Standard for Walk-in Cold Rooms. 0.3 The sectional committee responsible for the revision of this standard has taken into consideration the views of manufacturers, consumers and technologists and has related the standard to the current manufacturing trade practices followed in the country and abroad in this field. Due weightage has also been given to the need for international co-ordination among standards prevailing in different countries of the world. These conditions led the sectional committee to derive assistance from the following standards: a) B.S : 1979 Specification for manufacture of sectional cold rooms (walk-in type) issued by the British Standards Institution; b) ARI Standard : Unit Coolers for Refrigeration, issued by Airconditioning & Refrigeration Institute, USA; and c) ASHRAE Standard : Methods of testing forced convection and natural convection Air coolers for Refrigeration. 0.4 This standard is intended chiefly to cover the technical provisions relating to walkin cold rooms, and it does not include all necessary provisions of a contract. 0.5 For the purpose of deciding whether a particular requirement of this standard is compiled with, the final value, observed or calculated, expressing the rules of the test, shall be rounded of in accordance with IS: rules for rounding of numerical values (revised). The number of significant places retained in the rounded of value should be the same as that of the specified value in this standard. -i-

4 For BIS USE ONLY Not to be reproduced without the permission of BIS or used as a STANDARD Last date for the receipt of comments is 30 June 2007 Comments to be sent at: med@bis.org.in Draft Indian Standard SPECIFICATION FOR WALK-IN COLD ROOMS (first revision of IS 2370) 1. SCOPE 1.1 This standard covers the general constructional and performance requirements of walk-in cold rooms within the range of 5000 to litres gross volume capacity and operated by an electrically driven refrigerating machine of the vapor compression type. The methods of carrying out tests on walk-in cold rooms are also specified. 1.2 The limits of internal and ambient temperature covered by the standard are: Internal cabinet temperature 26ºC to +13ºC. Maximum ambient shade temperature + 46ºC. 2 REFERENCES The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this Indian Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below: IS No. Title IS 1068 : 1993 Electroplated coatings of nickel plus chromium and copper plus nickel plus chromium IS 325 : 1996 Three-phase induction motors IS 996 : 1979 Single-phase small ac and universal electric motors IS 9968 : Part 1 : 1988 Elastomer insulated cables: Part 1 For working voltages upto and including V IS 1401 : 1970 Accessibility test probes IS 302 : Part 1 : 1979 Safety of Household and Similar Electrical Appliances Part 1 General Requirements IS : 1988 Voltage Bands for Electrical Installations Including Preferred Voltages and Frequency 2. TERMINOLOGY 2.0 For the purpose of this standard, the following definitions shall apply. 2.1 Walk-in Cold Room A complete self-contained unit, into which a person can enter and reach any part inside, comprising: - 1 -

5 a) The insulated cold room, made in transportable sections; b) The Unit Cooler; and c) All auxiliaries, such as fans, lights, etc, the complete unit being capable of removal from one site and re-erection on another without interference with the main structure of a building. 2.2 Insulation (thermal) A material of low thermal conductivity employed for the purpose of resisting heat flow. 2.3 Transmittance (thermal) The quantity of heat flowing per unit time through unit area of wall or partition, divided by temperature difference between the air or other fluid on either face. 2.4 Unit Cooler Factory-made assembly, including means for forced air circulation and elements by which heat is transferred from air to refrigerant without any element external to the cooler imposing air resistance Unitary Unit Cooler comprises the condensing unit, the evaporator and fans for forced air circulation, valves and piping in a single cabinet Split Unit Cooler comprises the condensing and evaporating units in separate cabinets. 2.5 Vapour compression cycle A refrigeration cycle in which a refrigerant absorbs heat by evaporation and after being mechanically compressed, surrenders heat during liquefaction at higher temperature level. 2.6 Refrigerant The volatile fluid used in vapour compression cycle. 2.7 High pressure side The part of refrigerating system subject to higher or condenser pressure. 2.8 Low pressure side The part of refrigerating system subject to the lower or evaporator side. 2.9 Evaporator The part of refrigerating system, which performs the function of absorbing heat Condensing unit The part of refrigerating system, which is responsible for condensing the low pressure evaporated vapour to high pressure liquid refrigerant. It mainly comprises a power-driven compressor; a condenser and receiver, if any Unit Coolers A factory made assembly, including means for forced air circulation and elements by which heat is transferred from air to refrigerant without any element - 2 -

6 external to the cooler imposing air resistance. Unit cooler shall be unitary or split. The split unit cooler may be air-cooled or water cooled type Unitary Unit Cooler Unitary unit cooler consists of both evaporating unit and condensing unit in a single fabricated unit. These units may be window mounted or roof mounted Split Unit Cooler In Split unit cooler, the evaporating unit and condensing units are two separate units, which are connected together by refrigeration piping 2.11 Net total cooling effect The refrigeration capacity available for space and product cooling expressed in W [BTU/h] Gross total cooling effect- The heat absorbed by the refrigerant. This is the sum of the net total cooling effect and the heat equivalent of the energy required to operate the cooler Temperature Difference (TD) The difference between the dry-bulb temperature of the air entering the unit cooler and the saturation temperature corresponding to the refrigerant pressure at the suction connection of the unit cooler. 3. COLD ROOM 3.1 Inside dimensions Inside depth The inside depth shall be mean horizontal distance between the inside surfaces of the front and back inner walls of the lining Inside width The inside width shall be the mean horizontal distance between the inner surfaces of the floor and ceiling of the lining Inside height The inside height shall be the mean vertical distance between inside surface of the floor and ceiling of the lining Gross volume Gross volume shall be the product of inside depth, inside width and inside height. It shall be expressed to the nearest 50 litres up to litres and nearest 100 litres for sizes beyond litres. 3.2 Materials Materials used in the construction of the cold room shall comply with Indian standards where applicable, except where such requirements are otherwise modified by this standard. They shall be free from defects, which are liable to cause undue deterioration or failure

7 3.2.2 Under normal conditions of use, the materials used shall not shrink, warp or cause mould or odours, and shall be resistant to attack by vermin and destructive pests; where liable to be exposed to moisture, food products or chemically active substances, they shall be suitably resistant, and shall not contaminate stored products placed in contact with them. Sealing materials used shall not lose any of their essential properties, such as adhesion, plasticity and moisture resistance Interior and exterior finishes shall be durable and capable of being cleaned effectively and hygienically without undue deterioration. All metal parts used inside the cold room or on the outside, where they are liable to be exposed to moisture shall be corrosion resistant or adequately protected against corrosion. Finishes shall not crack, chip, flake, rub of or soften under conditions of normal service and cleaning Electroplated metal parts used in construction of sectional cold rooms shall conform to grade B of IS: For parts used internally, the standard shall be that for severe outdoor conditions or extra hard wear Cadmium plating shall not be used on any part of the storage space or its fittings Where vitreous enamelled parts are fitted, suitable means shall be provided to prevent chafing or mechanical stress likely to cause chipping. Where liable to contact with food products or their derivatives or other chemically active substances, the enamel shall be suitably resistant. 3.3 Construction The cold room and its parts shall be constructed with strength and rigidity adequate to normal conditions of handling, transport and usage All joints between sections shall be so formed as to become rigid and air tight after erection, and yet allow of the sections being dismantled and properly re-erected, if required Doors of the Cold room shall be arranged for access from both inside and outside. Where so desired, an electrical alarm signal may be provided in a convenient position The type and quality of gaskets and hardware used on access doors, hatches, plugs, etc, shall be such that efficient insulation is reasonably maintained Suitable provision shall be made to ensure that all external surfaces of the cabinet shall be reasonably free from condensation under normal conditions of service Internal linings and external fittings Linings and facings shall have sufficient mechanical strength to resist distortion and give reasonable protection to the insulation

8 3.3.7 Exclusion of air When the doors of the refrigerated space are closed there shall be no appreciable leakage of ambient air into the interior, either past the door gasket or by any other means Hardware Door fasteners and hinges shall be smooth and positive in action and designed to maintain their proper functioning without undue wear under normal conditions of service Drains Where drains are fitted they shall have ample capacity to cope with the requirements of normal service and shall be suitably sealed against ingress of air; they shall also be accessible for cleaning Interior fittings Hanging rails and shelves shall be of robust construction, rustproof and shall be adequately supported Minimum internal height The minimum height of cold room shall be 2 metres Minimum door opening sizes Unless otherwise specified the minimum clear opening size of door ways, shall be 1.8 m high x 0.7 m wide Thermal insulation The quality, thickness and application of the insulating material shall be such that efficient insulation of cold room is reasonably maintained. The whole of the external surface shall be sealed against moisture penetration by diffusion. Where the insulation space is vented to the inside, steps shall be taken to ensure that particles of the insulating material cannot escape into the storage compartment Where the moisture barrier is broken by door locks, pipes, hinges, etc, the points of entry shall be suitably sealed. Detachable plates and covers on the external surfaces shall also be provided with suitable seals against ingress of moisture into the insulation Where the internal / external surfaces are of high heat conducting materials, they shall be separated by insulating breaker strips or their equivalent, to ensure that all external surfaces shall be reasonably free from condensation under normal conditions of service Frame members within the insulation shall be kept to a minimum consistent with adequate constructional rigidity and loading applied in use. Where possible frame members shall not penetrate the full thickness of the insulation. 4. UNIT COOLER 4.1 Construction Pipes and connections to moving or resiliently-mounted parts shall be so arranged as not to foul or to transmit vibration to other parts. All other pipes and connections shall - 5 -

9 be secured and sufficiently free length shall be provided to minimize the risk of failure due to fatigue Where necessary under normal operating conditions, pipes and valves shall be thermally insulated. 4.2 Noise The refrigerating system shall be free from undue noise or vibration. 4.3 Water condensation Suitable means shall be provided to prevent water condensed on cold parts of the refrigerating system from effecting the operation of the unit or its controls. Suitable means shall be provided to prevent moisture dripping or splashing from baffles, drip trays or other cold parts on to the food or other products placed in the cold room. 4.4 Safety features in design (operation of safety device) The Refrigerating system shall be so designed that it will suffer no damage if a door, hatch or plug of the cold rooms is left open accidentally in ambient air of the temperature specified in the conditions of the contract (see 1.2). When the door or hatch is left open under normal operating conditions, the automatic overload protective device shall come into operation. 4.5 Control of operation Refrigerant flow and compressor driving motor operation shall be automatically controlled to reduce the cabinet temperature to the temperature specified and to maintain it within the limits of the application. 4.6 Location of components The evaporator and any associated screens, baffles, drip tray, etc, shall not obstruct access to stored products. All control devices and service valves shall be readily accessible. 4.7 Defrosting System Unit coolers which maintain room temperature below 0 ºC shall be provided with a suitable defrosting system to remove excess frost on the evaporator coil, which may affect the cooling capacity. This defrosting system shall operate automatically by means of a suitable controller. 5. ELECTRICAL EQUIPMENT 5.1 Rating of motors All motors shall be continuously rated and shall be suitable for the particular application. Motors, other than that of hermetically sealed compressor units, shall comply with IS: 325 or IS: 996, whichever is applicable. Motors of hermetically sealed compressor units shall be of adequate rating to comply with the test for adequate rating of compressor motors (see 6 ). For compressor motors an external over load relay shall be provided in addition to the inherent protection provided by the compressor manufacturer. 5.2 Motor overload protection Motor shall be adequately protected against dangerous over heating arising from excessive current. Small FHP single phase motors shall be provided with a fuse protection

10 5.3 All control gear shall comply with relevant Indian standards where applicable. 5.4 Cables and flexible cords Flexible supply cords and all cables used shall comply with IS: 9968(Pt 1) as regards thickness of insulation, insulation resistance, voltage test and, in the case of flexible supply cords only, color. The current carrying capacity of each cable and flexible cord shall be adequate for its full load current. Where a flexible supply cord passes through holes in metal parts such holes shall be shaped or bushed to protect the flexible cord from damage. 5.5 Wiring The wiring methods, together with the design, arrangement and workmanship employed, shall give full protection to the electrical insulation against mechanical damage from oil, heat, refrigerant, moisture or corrosive materials where these could be encountered. Conduit for internal wiring shall be adequately sealed against ingress of moisture Soldering fluxes shall not cause corrosion. 5.6 Accidental Contact Live parts shall be protected by suitable guards, shields or screens of adequate strength and durability so that there is no possibility of making inadvertent contact under normal service conditions. It shall not be possible to touch live parts with the accessibility test probes following the procedure described in IS: 1401 even after the removal of covers or casings which can be removed without the use of tools, or during replacement of the lamp. 5.7 Internal Electrical Components Internal lamps shall be mounted in suitable fittings and provided with guards for protection against mechanical damage. Internal fans shall be suitable for operation at the lowest air temperature likely to occur. 5.8 Earthing Metal casings of the electrical components, metal frame and all exposed metallic parts likely to become alive shall be provided with earthing facilities in accordance with the requirements given in IS: Standard Rating Conditions for Unit Coolers for Refrigeration Group Number Inlet Air Temperature Dry-bulb Wet-bulb o C o C Nominal Relative Humidity Saturated suction Temperature I. High % 1.7 II.Medium above Freezing III.Medium below Freezing IV. Low

11 7. Classification of Tests Tests shall be classified into three groups, namely, (a) Production Routine Tests; (b) Type Tests; and (c) Acceptance Tests. 7.1 Production Routine Tests These shall consist of routine tests that would be conducted on each and every unit after completion at the manufacturer s works General Running Test Each unit shall be given a run to ensure vibration free and satisfactory operation of mechanical parts Pressure Tests: The manufacturer shall test all parts of the refrigerating system to pressures not less than those given in Table TABLE 1 MINIMUM TEST PRESSURES (Clause 7.1.2) REFRIGERANT CHEMICAL HIGH LOW FORMULA PRESSURE PRESSURE SIDE SIDE Kg/cm 2 Kg/cm Ammonia NH R-12 CCl 2 F Methyl Chloride CH 3 Cl R 22 CH Cl F R 134a CH 2 FCF R 404A No part of the assembly under test shall show signs of leakage or permanent distortion after being subjected to the above tests for a period of not less than two minutes

12 7.1.3 Electrical Tests of Unit Cooler: a) Insulation Resistance The insulation resistance between all electrical circuits and the earthed metal parts when measured at normal room temperature with a voltage of not less than 500 V DC shall be not less than one mega ohm. b) High potential test The normal insulation of all electrical circuits at room temperature shall be such as to withstand a High-potential test of 2000 V RMS applied for not less than five seconds between all circuits and accessible metal parts. For refrigerating machinery to be connected to circuits of 50 V and below the highvoltage test shall be 500 V RMS. The test voltage shall be alternating, of approximately sine wave form and of any convenient frequency between 25 and 100 cycles per second. 7.2 Type Tests The type tests shall consist of the tests that would be necessary to check the performance and characteristics of the units and components and shall be carried out by a recognized testing authority, who may be the manufacturer, if approved by the purchaser. Once a walk-in cold room has undergone type tests, any major or essential alterations, which the manufacturer intends to make, shall be reported to the testing authority and further type tests shall be carried out in accordance with the procedure laid down in this standard Besides all the production routine tests specified in 7.1, the type tests comprise the following Cold Room Door Seal Test Door or hatch seals shall be tested to ensure that the gasket or gaskets will grip on a strip of paper not more than 50 mm wide and 0.08 mm thick when the door is closed normally on it Thermal insulation The insulated structure of the cold room after assembly shall be tested by the heat-input method to determine its thermal transmittance. For this purpose the interior of the cold room shall be heated by an electrical heater (or heaters) suitably shielded to prevent radiation to the walls and so located as to ensure a uniform temperature of not less than 14 ± 1 C above the ambient temperature outside the test room and maintained at that temperature for 30 hours

13 The record of electrical energy input and inside and outside temperatures shall be taken hourly during the last six hours. From this record, we can compute the heat dissipation from the cold room to the outside ambient, from which we can calculate the thermal transmittance. The thermal transmittance shall not exceed the value specified. Thermal Transmittance = Q x 1000 / 6 A (t o t i ) Where Q = kwh recorded for 6 hours A = Mean area of cold room walls & ceiling and t o, t i are the average outside and inside temperatures respectively Unit Cooler The tests as per , , and shall be carried out on the fully assembled unit cooler with all its panels, fittings and standard accessories (if any) in place Measurement of air-flow (CFM) The evaporator air flow shall be measured at rated voltage and frequency with a calibrated anemometer. Air flow = A x v, m 3 / hr where A = area over which at least 16 anemometer readings are taken at equispaced locations m 2, and v = mean velocity of air, m/hr Capacity Rating Test a) Method 1 The cooling capacity may be determined by using the enthalpy change of the refrigerant across the cooler and the refrigerant mass flow rate. Any enclosure in which the specified test conditions can be maintained within a tolerance of ± 1 ºC may be used to determine cooling capacity. Refrigerant side gross cooling capacity can be computed by the product of mass flow rate of refrigerant and the enthalpy difference at the inlet and outlet of the cooler. Enthalpies at the inlet and outlet of the cooler can be read off the standard P-H chart or tables based on the refrigerant inlet and outlet conditions

14 Refrigerant flow shall be measured by a refrigerant flow meter with an accuracy of 2% of the quantity measured. Net cooling capacity can be found by gross cooling capacity minus (E c + E). b) Method 2. This method determines the cooling capacity of a unit cooler by measuring the electrical input to a calibrated box so as to maintain specified temperature and humidity conditions inside the calibrated box at a specified outside ambient temperature. The size of the calibrated box shall be such that it shall not restrict the normal flow of air around the equipment to be tested. In no case shall the heat leakage of the calibrated box exceed 30% of the gross total cooling effect of the air cooler under test. For forced circulation unit coolers, Air side gross cooling capacity can be found by q ta = K c (t 4 t 3 ) + E c + E, Watts q ta = Air side gross cooling capacity, Watts K c = heat leakage coefficient of calibrated box, (W/ ºC) E c = total electrical input to heaters and auxiliary equipment of calibrated box, W E = total electrical input to fan motor(s) of Unit Cooler, W t 4 = average dry-bulb temperature of air surrounding the calibrated box, (ºC) t 3 = average dry-bulb temperature of air within the calibrated box, (ºC) Net cooling capacity can be found by gross cooling capacity minus (E c + E) Calibration of the Calibrated box: The heater input shall be adjusted to maintain an average box temperature not less than 14±1 ºC above the outside surrounding temperature. The box temperature shall be taken as the average of all readings. A calibration test shall be the average of eleven consecutive hourly readings that fall within the limits specified by this standard. A calibration test shall be made for the maximum and the minimum forced air movements expected in the use of the test box. The calibration heat leakage shall be plotted as a straight line function of these two air quantities and this curve shall be used as calibration for the box. The calibration heat leakage of the calibrated box shall be computed as described in clause

15 Fig. 1 Calibrated box method Power Consumption test: The power consumption of the Unit Cooler shall be measured during the capacity rating test at the Standard Rating Conditions given in 6. NOTE: Attention is drawn to IS: where it is recommended adoption of 240 volts single phase in place of 230 volts single phase. In the interim period, however, 230 volts single phase will be permissible voltage Maximum operating condition test is conducted at an outdoor ambient temperature of 46 ºC and at specified indoor temperature (clause 6). The Unit Cooler shall operate for at least 2 hours without tripping of the compressor or any of the safety controls. 7.3 Acceptance Tests If the purchaser desires any of the production routine tests to be repeated at the time of purchase, where agreed to between the purchaser and the manufacturer, the tests may be carried out at the manufacturer s works. Alternatively, the tests may be repeated at the place specified by the purchaser

16 7.4 Preparation of units for tests Preparation of selected units a) The cold room and unit cooler shall be installed as in normal service. All permanently located accessories shall be in their proper places but the storage space shall otherwise be empty during all tests except as limited by the test conditions herein stated. b) Before the unit cooler is put on test, it shall be given a minimum run-in period of 12 hours. 7.5 General requirements for tests Test conditions a) The sectional cold room shall be so placed or shielded as to prevent direct radiation from the heating equipment. Air circulation in the test room shall be such that the specified uniformity of temperature distribution is obtained without a direct draught upon the room under test. Windows in the test room shall be provided with suitable radiation shields. The cold room shall be shielded from extraneous air currents which exceed 15 m per minute. b) The interior of the cold room shall be dried immediately before the stabilization period preceding the tests. c) The cabinet door (or doors) shall be kept closed during each test Temperatures Ambient temperatures a) Outside ambient temperature shall be maintained to within ± 1.5 ºC of the specified value, and shall be measured at points located at 1 m from the floor and 0.25 m from the sides and front of the cold room. This condition shall be maintained during both stabilizing and test periods. b) The ambient temperature shall be recorded at one of the above positions, preferably with a recording instrument. If an indicating instrument is used, readings shall be taken at intervals of 30 minutes. c) The vertical temperature gradient from the floor to a height of 2 m shall not exceed 1.5 º C for each meter of vertical distance Internal cold room temperature a) Temperature of the cold room air shall be measured in at least six representative positions and the mean shall be taken as the cold room temperature

17 b) All the temperature measuring elements shall be supported in the cold room in such a manner that there will be at least 13mm of air space separating the thermal element from contact with heat conducting surfaces in the cold room. Connections from the temperature measuring elements shall be brought to the outside of the room in such a manner as to interfere as little as possible with air seals. c) The inside temperature shall be maintained to within ±1 o C Electrical supply The condition specified for tests shall be average values within the following variations: a) ±2 percent of standard voltage b) ±1 percent of supply frequency Instruments and measurements a) All instruments used for measuring shall be calibrated against a secondary standard before making each test or series of tests. b) Temperature measuring instruments shall be accurate to 0.3º C. c) The operating time of the unit shall be obtained by means of a recording meter or a self-starting synchronous electric clock. 8. MANUFACTURER S GUARANTEE The manufacturer shall give a guarantee for the soundness of construction and performance of the cold room, and shall be responsible for putting right any manufacturing defects free of charge for a period of twelve months from the date of sale to the original purchaser or date of inspection or approval in the case of government or semi-government institutions, it being understood that such repairs or replacements of defective parts to be carried out at the manufacture s works. 9 MARKING 9.1 The sectional cold room shall have the following information marked on a nameplate in permanent and legible manner in location where it is accessible and visible: a) Name of the manufacturer or sponsor of the complete assembled unit; b) The voltage rating and normal running current of the Unit Cooler ; c) The name and the maximum weight of the refrigerant used ; d) Type, model, catalogue and serial number of the cold room compressor, motor, etc, or sufficient information to provide adequate identification for replacement of parts or necessary servicing ; 9.2 The following information shall be provided by the manufacturer or the sponsor of each complete unit, not necessarily in a permanent marking:

18 a) Operation instructions, b) Internal volume, and c) Net storage surface. 9.3 Each walk-in cold room may also be marked with the Standard Mark The use of the Standard Mark is governed by the provisions of Bureau of Indian Standards Act, 1986 and the Rules and Regulations made there under. The details of conditions under which a license for the use of Standard Mark may be granted to the manufacturers or the producers may be obtained from the Bureau of Indian Standards