lS:660-1963

( Reafficd 19% )

Indian &mdard
SAFETY CODE FOR
MECHANICAL REFRIGERATION

( Revised )

Eighth Reprint MARCH 1999

UDC 621.56: 614.8

@ CopVright 1963

BUREAU OF INDIAN STANDARDS

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MAHG
NEW DELHI 110002

Gr 4 August 1963
 IS:660-1963

Indian Standard
SAFETY CODE FOR
MECHANICAL REFRIGERATION

( Revised )

Refrigeration and Air Conditioning Sectionai Committee, BDC 18

Chairman Re@rascnting
SHRI J. C. KAPUR Air-Conditioning Corporation Ltd, Calcutta; oad
Air-Conditioning and Refrigeration Council of’
India
A4embcrs
Snnr MORAN T. ADVANI Blue Star Engineering Co ( Bombay ) Private Ltd,
Bombay
SHRI RAM D. MALANI ( Altrmalc 1
Saw Y. D. &IIJJA The Economy Refrigeratiop and Enginceriirg
Co Ltd, Bombay
SHRI N. BALASUBRAMANIAN Voltas Ltd, Bombay
SERI K. V. RAMAN ( Al&mole )
LT S. N. BHAH~AVA Naval Headquarters
SHRI S. K. BHATTACRARYA Central Public Works Department
Saa~ S. K. CHAUDHURY Ministry of Food & Agriculture
SERI N. K. D. CHOUDEURY Central Building Research Institute ( CSIR ),
Roorkee
SHRI B. C. RAY CHOUDHURY ( Al&mute )
SHRI P. N. DEOBEAKTA Development Wing ( Ministry of Economic &
Dcfence Co-ordination )
SHRI A. N. .MUKHERJEE ( Allcmate )
SHRI K. C. JERATH Engineer-in-Chief’s Branch, Army Headquarters
Snar G. K. KABRA The Hyderabad Allwyn Metal Works Ltd,
Hyderabad
SHRI H. J. LENTIN Godrej & Boyce Mfg Co ( Private ) Ltd, Bombay
SURQ-Coal M. S. MALIIOTXA Ministry of Defence ( R & D )
SH~I NAUNIHAL S~NGHMATIKUR National Physical Laboratory ( CSIk ), New Delhi;
and Indian Society of Rrfrigcrating Engineers,
Calcutta
SHRI A. P. SHIVDASANI Indian Society of Rcfrigcrating Engineers, Calcutta
( Alfcrnate )
SHRI S. N. MUKERJI Government Test House, Calcutta
San: 8. K. B~UKRERJEE ( Alkrnatc )
( Conlinud on page 2 )

BUREAU OF INDIAN STANDARDS

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARC
NEW DELHI 110002
IS I 660 - 1963

Members Representing
SHRI AMAR SINon NAGIU Railway Board ( Ministry of Railways )
SHRI C. B. PATEL National Buildings Organisation ( Ministry of
Works, Housing & Rehabilitation )
SHRI V. D. TIWAIU ( Alfcrnofc )
SARI K. N. R. PILLAR Directorate Grneral of Posts & Telegraphs
( Ministry of Transport & Communications ),
Jahalpur
SHBI K, R. D. IYt?NoAR ( AIlrrnale )
SARI R. BAI.ASZTBRAMANIAM ( Alternote )
SHRI B. J. RI% \KHIANI Ministry of Labour
SHRI u. s. SAX Ascoon Directorate General of Supplies & Disposals
( Ministry of Economic & Defencc Co-ordination)
SRRI D. T. GURSAHANI ( AIfernate )
DR H. C. VISVESVARAYA, Director, IS1 ( Ex-o&o Member)
Deputy Director ( Bldg )

Secretmy
Snnr C. R. RAMA Rio
Assistant Director ( Bldg), IS1

Commercial Equipment Including Safety Standards

Subcommittee, BDC 18 : 2

Convener
SHRI S. K. BHATTAC~ARYA Central Public \Yorks Department

SHRI P. C. MALKANI ( Alternate to

Shri S. K. Bhattacharya )
SHRI R. AIYADURAI Refrigerators & Home Appliances ( Private ) Ltd,
Madras
SHRI R. RAMACHANDRAN ( Alfcrnate )
SERI S. K. CHAUDHURY Ministry of Food and Agriculture
SHRI NAUNIHAL SIN(:I~ MATHUR Indian Society of Refrigerating Engineers,
Calcutta
SHRI A. P. S~IV~ASANI ( Alternafe )
SHRI D. R. MEHTA Capital Refrigeration Co, New Delhi
SHRI R. N. SETH Blue Star Engineering Co ( Bombay ) Private
Ltd, Bombay
SHRI S. A. SHAlI American Rrfrigerator Co Ltd, Calcutta

2
 h&an Standard
SAFETY CODE FOR
MECHANICAL REFRIGERATION

0. FOREWORD
0.1 This revised Indian Standard was adopted by the Indian Standards
Institution on 5 August 1963, after the draft finalized by the Refrigeration
and Air Conditioning Sectional Committee had been approved by the
Building Division Council.

0.2 The need for laying down safety requirements for mechanical
refrigeration equipment has been well recognized with a view to
safeguarding life and health of persons working in the plant rooms and
also to protect the property. This standard consequently issued in 1955,
covered the safety features of the design, construction, installation,
operation and inspection of mechanical refrigeration systems including
working conditions in the plant rooms which are considered reasonably
necessary to safeguard life, health and property. After reviewing the
standard in the light of the experience gained during its usage, this
revision has been prepared incorporating the following important changes.

0.2.1 Recommendations have been added to give guidance on charging

of the refrigerants. Modifications have been made to indicate the
positions where the stop valves have to be provided on compressor,
receiver and evaporator. References have been added to relevant Indian
Standards which have been recently issued. The pressures at which
pressure-relief devices should be set to blow off have been modified so as
to relate them to the minimum field refrigerant leak test pressures.
Incidentally, opportunity has been taken to specify ail the values in metric
system.

0.3 The Sectional Committee responsible for the preparation of this

standard has taken into consideration the views of producers, consumers
and technologists and has related the standard to the manufacturing and
trade practices followed in the country in this field. Due weightage has

3
 ISr660-1963

also been given to the need for international co-ordination among stand-
ards prevailing in different countries of the world.

0.4 Wherever a reference to any Indian Standard appears in this code, it

shall be,taken as a reference to its latest version.

0.5 Metric system has been adopted in India and all quantities and
dimensions in this standard have been given in this system.

0.6 For the purpose of deciding whether a particular requirement of this

standard is complied with, the final value, observed or calculated, express-
ing the result of a test, shall be rounded off in accordance with IS : 2-1960
Rules for Round,ing Off Numerical Values ( Revised ). The number of
significant places retained in the rounded off value should be the same as
that of the specified value in this standard.

0.7 This standard is intended chiefly to cover the technical provisions

relating to the safety features of the installations, operation and mainten-
ance of mechanical refrigeration systems, and it does not cover all the
necessary provisions of a contract.

1. SCOPE

1.1 This code covers safety features in the design, construction, installa-
tion, operation and inspection of mechanical refrigeration systems of
vapour compression type, including working conditions in the plant room,
which are considered reasonably necessary to safeguard life, health and
property.

2. TERMINOLOGY

2.0 For the purpose of this code, the following definitions shall apply.
2.1 Compressor - The equipment in which refrigerant in a refrigerating
machine is compressed to increase its pressure before liquefaction.

2.2 Condenser - A part of the refrigerating system where high pressure

refrigerant gas is condensed to high pressure liquid.

2.3 Condensing Unit - A combination of equipment consisting mainly

of compressors, condensers and liquid receivers ( when required ) for
converting low pressure gas to high pressure liquid.

4
 IS:660-1963

2.4 Evaporator - A part of the refrigerating system where liquid rcfri-

gerant is evaporated to produce cooling.

2.5 Expansion Value - A valve which makes the liquid refrigerant to’
expand from a high pressure to a low pressure and controls the flow of the
refiigerant.

2.6 Fusible Plug - A plug made of special fusible alloy which fuses at a
predeiermined temperature and relieves pressure in the refrigerating
system.

2.7 High Pressure Switch - An automatic protective device against

excessive pressure on the high side. It automatically stops a compressor
or a condensing unit when the pressure on the high side exceeds a
predetermined limit.

2.8 Low Pressure Switch - An automatic protective device against

excessively low pressure on the low side. It automatically stops a com-
pressor or a condensing unit when the pressure on the low side falls below
a predetermined limit.

2.9 Plant Room - Room in which a refrtgerating plant, other than

domestic refrigerating appliances such as refrlgeratars, portable air condi-
tioners, etc ( which are installed inside the living room ) is installed and
operated.

2.10 Pressure Relief Device -A pressure actuated valve or device which

automatically relieves the pressure in excess of its setting.

2.11 Pressure Vessel-It is a receiver containing refrigerants under

pressure.

2.12 Receiver -A vessel forming a part of refrigerating system acting

as a receptacle for liquid refrigerant.

2.13 Refrigerant - A chemical agent used to produce cooling by

expansion from high pressure liquid to low pressure gas in a refrigerating
system.

2.14 Refrigerant Container - A vessel for storage of liquid refrigerant.

2.15 Refrigerating System - An equipment consisting of condensing

unit and evaporator in which refrigerant is circulated to extract and
transfer heat.

5
18:660-1963 G

3. INSTALLATION REQUIREMENTS

3.1 Plant Room

3.1.1 Doors, Partitions and Openings -The plant room of each
refrigerating system shall be provided with a door( s ) and shall have,no
partitions or openings so as to avoid escape of refrigerants to other parts
of the building.

3.1.2 No plant room door shall have locking devices from inside.
However, facilities for bolting from inside may be provided.

3.1.3 Adequate ventilation shall be provided for each plant room. The
ventilation required shall generally be in accordance with Table I. To
achieve the required vemilation, windows or doors opening to outside
air or power driven exhaust fans may be provided. The sizes of the
windows and doors and air displacing capacity of the exhaust fans shall
be in accordance with the requirements given in Table I. When exhaust
fans are used, provision should be made for inlet of the air to replace the
air that is being exhausted by the fan. The area of the duct if connected
to the exhaust fan or fans shall be in accordance with the minimum duct
areas as given in Table I.

3.1.4 Emergency Exit and Fire Extinguisher - Each plant room shall be
provided with emergency exits and fire extinguishers of suitable type ( see
*I!j:2190-1962 Code of Practice for Selection, Installation and Main-
tenance of Portable First-Aid Fire Appliances).

3.1.5 First-Aid Equipment - Fist-aid equipment shall be provided in each

plant room in accordance with the requirements laid down in the Indian
Factories Act, 1948, and the Rules thereunder.

3.1.6 Gas Masks-One or more gas masks or breathing apparatus of

suitable type shall be kept immediately outside the plant room in an
accessible position. Canisters of the gas masks shall be renewed
periodically.

3.2 Foundation and supports provided for condensing units or compressor

units or other refrigeration equipment shall be substantially sound and
vibration absorbing and of non-combustible construction.

3.2.1 All moving machinery shall be guarded in accordance with thr

provisions of the Indian Factories Act, 1948, and the Rules thereunder.
3.3 Adequate clear space for inspection and servicing of condensing units
or compressor units shall be provided.

lSince revised.
6
 IS:660-1963

TABLE I MINIMUM AIR DUCT AREAS AND OPENINGS

( Clause 3.1.3 )
WEIGHT OF THE MECHANICAL DUCT AREA OPEN WIN DOW
REFBIGEBANT DISCHARGE oa DOOR ABEA
IN THE SYSTEM OF AIR
(1) (2) (3) (4)
kg ms/min m2 m2

:05 3.9
7.1 0.025
0.05 812
50 11.3 0.05
1g 18’0
148 0.07 ;:;

125 20.8 0.10 ;:;

150 23.5 0.10
z: 28.5 0.12 ;:;

300 :z 0.14 22::

% 41
45 0.18 2.6
2.8
450 49 0.18 3.0
% z: 0.20 3.1

66 ;:;
;: oo:$
:; 0.20 ;:;
1:g 83 0.20
1 250 97 0.28 ;:o”
1 500 109 0.35 5.4
2000
2500 132
154 ::z ;:;
3000 173 0.50 7.7
3 500 192 0.54 8.3
4 000 210 o-58 8.8
4500 227 0.60 9.4
5000 244 0.65 9.9
6 000 275 0.70 10.8
7000 305 0.72 11.7
8 000 333 0.75 12.5
9000 361 0.78 13.3
10 000 387 0.81 140
12 000 437 0.83 153
14 000 484 0.84 16.6
16 000 529 0.86 17.7
18 000 572 188
20 000 614 Kz 20.0
~Y~TE 1 - Mechanical discharge of air and open area hnvc been derived
from the following formula: taken from DIN 8975 Refrigeration Plants,
Safety Principles for Their Construction, Equipment and Erection:
Open window or door area, rn? = 0.14d E
Mechanical discharge of air, ms/h = 5OeD
where
C is the charge in kg of the largest closed circuit of refrigerant
present in the engine room.
NOTE 2 - Intermediate values may be obtained by calculation.

7
3

I8 t 660 - 1963

3.4 Condensing units~ or compressor units within enclosures shall be

readily accessible for inspection and servicing.
33 Adequate illumination for inspection and servicing of condensing
units or compressor units and other refrigeration equipment shall be
provided.
3.6 Water supply connection shall be made in accordance with the
requirements given in*IS i2065-1963 Code of Practice for Water Supply in
Buildings.
3.6.1 Water used for removing heat from the refrigerating system shall
not be discharged into any water supply which is likely to be used for
human or animal consumption.
3.7 Electrical wiring and installation of the electrical equipment shall be
in accordance with the requirements of the Indian Electricity Act, and
Rules thereunder and shall also conform to the requirements laid~ down
in IS : 732-1963 Code of Practice for Electrical Wiring Installations
( System Voltage Not Exceeding 650~ Volts ) ( Revised), IS : 2274-1963
Code of Practice for Electrical Wiring Installations ( System Voltage
Exceeding 650 Volts ) and i,IS : 302-1960 General and Safety Require-
ments for Light Electrical Appliances, as applicable.
3.7.1 Electrical interlocking of the compressor with condensing water
pump and cooling tower fan ( where provided ) is strongly recommended.
The switch of the compressor moter should be interlocked with the pump-
ing set and fan in such a way that the compressor motor will not start
until the condensing water pump and fan have started.
3.7.2 It is recommended that as far as practicable the high pressure
switches, low p:essure switches, and other electrical control apparatus
used in connection with a mechanical refrigeration system be operated
on a voltage not exceeding 250.

3.8 No open flame or apparatus to produce open flame or hot surface

above 425°C shall be permitted in a plant room having one or more
refrigeration machines with a total refrigerant charge exceeding that
mentioned in Table II for each cubic metre of room volume.

3.9 No open flame shall be applied to refrigerating system or refrigerant

vessel when the system or vessel is charged with refrigerant.

3.10 In the case of refrigerating system using in@nmable refrigerants,

such as methyl chloride; ethane, etc, all electrical installations for
refrigerating system shall generally conform to the requirements given
*Since rcviscd.
*‘Third revision in 1967

8
 IS : 660- 1963

TABLE II MAXIMUM PERMISSIBLE QUANTITIES OF INFLAMMABLE

REFRIGERANTS

( Clause 3.8 )

NAME CHEMICALFOIIMULA MAXIMUMQUANTITY

g/m3
Butane Coho 40
Ethane C&4 40
Ethyl chloride CsHsCI 100
Ethylene C&4 32
Isobutane (CH313CH 40
Methyl chloride CH,CI 160
Methyl formate HCOOCH, 110
Propane C3Hs 40

in IS : 1646-1961 Code of Practice for Fire Safety of Buildings (General):

Electrical Installations, where applicable, and any othere fire safety
requirements laid down by the appropriate authority.

3.11 No refrigerating system or piping shall be installed in a passage

doorway, below a staircase, or in any public place, except when suitably
guarded.

3.12 Charging of Refrigerant - While charging, a gauges hould be provided

between the refrigerant container and the machine to know the pressure
at which the system is being charged. This pressure should not exceed the
discharge pressure at which the compressor has to work with particular
type of refrigerant.

3.13 For each installation of refrigerating system, t’le following informa-

tion, mounted on a frame, should be clearly posted in the plant room :

a>Name and make of the condensing unit;

b) Model of condensing unit;
Cl Name and full charge of refrigerant;
4 Full charge of oil;
4 Quantity of refrigerant and oil charged in the system with clatc of
charging;
f > Pressure at which the system is tested after installation; and
d Change of refrigerant, if any, with date.

9
ISr660-1963

4. REFRIGERATING SYSTEM AND EQWMENT

4.1 Refrigerant piping, valves, fittings, their related parts and all material
used in the construction and installation of refrigerating system shall be
suitable for the refrigerant used. No material which would deteriorate
due to chemical action of the refrigerant or the oil or the combination of
both and moisture shall be used. Aluminium, zinc or magnesium shall
not be used in contact with methyl chloride. Magnesium alloys shall
not be used in contact with chloro-fluoro derivatives of methane and
ethane. Copper and copper alloys shall not be used in contact with
ammonia.

4.2 AU joints shall be readily accessible.

4.3 Joints from refrigerant copper pipe and fittings made with solder or
other alloys shall have melting point of :

a) not less than 260°C for pipe sizes up to 32 mm, and

b) 540°C for pipe sizes above 32 mm and for all the sizes on hot gas
lines.

4.4 Stop valves shall be installed on all systems other than those using
centrifugal compressors, containing more than 10 kg of refrigerant. The
location of the stop valves shall be as given in 4.4.1.

4.4.1 Stop valves shall be provided at the inlet and outlet ends of each
of compressor, receiver and evaporator.

4.5 Test Pressures - All stop valves, piping, joints, flanges and fittings
shall withstand test pressures as given in Table III after completion of
installation and before operation.

4.6 All refrigerant piping should be supported by means of hangers,

bracket straps, clamps, clamps of pedestals in such a manner as to relieve
joints of harmful strains and vibrations.

4.1 Colour identification of refrigerant pipe lines shall be in accordance

with the colour identification given in IS : 2379-1963 Colour Code for
Identification of Pipe Lines.

4.8 Emergency I)ischarge Line - Each refrigeration system of ammonia

and sulphur dioxide having a charge of 10 kg or more should be equipped
with emergency discharge line. The discharge line should be connected
directly on top of the receiver or the condenser receiver. The emergency

10
 IS : 660 - 1963

TABLE III MINIMUM FIELD REFRIGERANT LEAK TEST

PRESSURES
( Clauses 4.5 and 5.3 ),

NAME OF CHEMICAL MINIMUM FIELD REBRIQERANT

REBRIOERANT FORMULA LEAK TEST PREBSUBEB,
kg/cm2 GAUCJE
~------A------\
High Pressure Low Pressure
Side Side

Ammonia NH3 20 10.5

‘Carbon dioxide CO2 100 70
Dicblorodifluoromethane CC12F2 16 10
Dichloroethylene C2HzC12 2 2
bichloromethane (methylene
chloride) CH2C12 2 2
Dichloromonofluoromethane CHC12F 5 3
Dichlorotetrafhroroethane C2C12F4 3.5 3.5
Ethane C2He 85 50
‘Methyl chloride CH,Cl 15 8.5
Monochlorodifluoromethane CHClF2 20 10.5
lSulpbur dioxide so2 12 6
Tricbloromonofluoromethane CCI,F 2 2
Trichlorotrifluoroethane C2C13F3 2 2

‘Not recommended for new installations.

valve should be placed immediately outside the plant room and there
should be no valve between the emergency valve and the receiver so that
in case of an emergency the valve can be operated from outside without
entering the plant room. Adequate precautions should be taken to see
that the emergency valve is not tampered with by any unauthorized
person. The emergency valve should be covered preferably with a glass
fronted box. The emergency discharge pipe should be so connected
outside the building that it does not affect the surrounding locality.
5. PRESSURE DEVICES
5.1 High Pressure Switch
5.1.1 AIl*condensing units or compressor units above the sizes normally
used for domestic refrigerators shall be fitted with automatic high
pressure switches.

11
ISt660-1963

5.1.2 The hi h pressure switch shall always be fitted on to the

discharge side o tgthe compressor before the discharge shut-off valve.
5.1.3 For condensing units about 7.5 ‘kw the cut-in cycle of the high
pressure switch shall not be automatic, that is, after tripping, the com-
pressor motor shall require to be started manually.
5.2 Low Pressare Switch - Low pressure switch should be fitted,
wherever practicable, to all compressors other than those used for
domestic refrigerators when the compressors are used for producing low
,temperature conditions below 0°C.
5.3 Pressure Relief Devices or Fusible Plugs - These shall be provi-
ded on the l$gh side above the refrigerant liquid level on all condensing
units. The discharge for the relief valve should be so connected that
it should discharge without affecting the surrounding locality outside the
building. Ammonia and sulphur dioxide refrigerants shall be discharged
in vessels containing wat& and brine, respectively. The pressure relief
valves shall be set to blow at pressures 75 to 80 percent of those specified
for minimum field refrigerant leak test pressures ( on the high pressure
side ) given in Table III.

6. PRESSURE VESSELS

6.1 All refrigerant-containing pressure vessels’ shall be hydrostatically

tested and thoroughly examined periodically as required under the
Factories Act, 1948, and the Rules thereunder.
6.2 All refrigerant-containing pressure vessels having a net volume of
0*15m3 or more, and which may be shut off by valves, shall be equipped
with pressure relief devices or fusible plugs.

7. MAINTENANCE

7.1 Each refrigerating system after installation shall be checked for

refrigerant leaks every three months.
7.2 Pressure devices, pressure gauges and all other refrigerant controls
on both the high side and low side shall be checked periodically, the time
between two such inspections not exceeding six months. Fusible plugs
shall be inspected once every three months.
7.3 Moulds, cans, tanks, etc, shall be checked frequently for chemical
action and corrosion from hygienic and sanitary point of view.
7.4 Electrical installation shall be checked periodically for insulation
leakage, etc, in accordance with the Indian Electricity Act, 1910, and

12
 18:660-1963

the Rules thereunder and IS : 732 - 1963 Code of Practice for Electrical
Wiring Installations (System Voltage Not Exceeding 650 Volts) ( Rmid )
and IS : 2274 - 1963 Code of Practice for Electrical Wiring Installations
( System Voltage Exceeding 650 Volts ).

7.5 All repairs shall be duly recorded and a record of all tests carried out
after repairs shall be maintained. The record should be signed by the
mechanic and the engineer or officer-in-charge.

7.6 Proper precautions shall be taken that no gas other than what is in
the system is charged.

7.7 Open flame shall never be applied to the gas cylinder or to the
system when it is charged with refrigerant.

7.8 In a plant room in which refrigerating system containing more than

25 kg of refrigerant is installed, a card shall be placed conspicuously near
the compressors giving directions for the operation of the refrigerating
system including precautions to be taken in the case of a breakdown or
leak and instructions for shutting down the refrigerating system in case
of emergency.

13
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