AMMONIA COMPRESSORS AND REFRIGERATION Plant From Jakarta Pusat
INTRODUCTION
1 A well known circular gives advice on the precautions to be taken against the toxic, fire and boom hazards presented by refrigeration systems containing ammonia. These are around likely to be commence by LA enforcement officers at analytic stores and food shipment warehouses. It applies to the complete system not simply the compressor house. It provides temporary advice on matters of angst to enforcement officers pending analysis of BS 4434:1980.
2 Appendix 1 outlines the modern principles of refrigeration, Appendix 2 gives aid on the results of the programme of peculiar visits carried out in 1983 by Factory Inspectorate (F1) to acknowledge present standards in the food industry and Appendix 3 gives correct guidance on electrical standards. Imposition officers should not overemphasise the hazards of ammonia compared amidst other refrigerants.
HAZARDS
Toxicity
3 Ammonia is a chemically reactive ammunition that is very soluble in water and is much lighter than condition (vapour density 0.59 of a well known of air). Cold vapour (e.g. from leaks) may anyhow be denser than air. Admitting there have been incidents of danger to harmful concentrations of ammonia in the UK ready have been few alarming accidents. Ammonia is characterised by a typical pungent odour and is visible by most people at levels of about 50 ppm in the atmosphere. Despite workers become tolerant to a certain effect and in the past have been able to employment without distress at levels up to 70 ppm, at present the recommended exposure length for ammonia is 25 ppm, 8 age TWA (0.0025%) and the faultfinding term exposure limit is 35 ppm, 10 dwarf TWA. At 400 ppm, around people experience immediate beak and throat irritation, however suffer no permanent ill-effects afterwards 30-60 minute exposure. A classification of 700 ppm causes immediate irritation to the eyes, and a classification of 1,700 ppm (0.17%) resolve give rise to fixed coughing and can be critical after about 30 minutes exposure.
Exposure to concentrations superior 5,000 ppm (0.5%) as quite short periods bag result in death. Consequence to the effects of ammonia varies widely betwixt individuals, and the dose-response effects described raised are likely to be those expert by the more clear members of the population.
Fire and explosion
4 Ammonia forms a flammable concoction with air at concentrations between 16 and 25% v/v. There have however been literally few incentive explosions involving ammonia compressor houses in the UK and anyone of the reported incidents absorbed ammonia leakage from bury under maintenance.
Existing guidance
5 Present-day guidance on the precautions which should be taken with ammonia refrigeration plant may be commence in: British Standard 4434: 1980 "Requirements as Refrigeration Safety: Part 1, General". The requirements (particularly from the f ire and bang standpoint) are similar to those in the leading (1 969) version. Ever a' full revision of BS 4434 is taking place.
Precautions
6 Concealed by normal circumstances people resolve not be able to allow ammonia concentrations at constant a fraction of the flammable limit. The applicable precautions are mainly those applicable against toxic effects in occupied areas and to field where sudden exposures are foreseeable, aforesaid as maintenance and fitness work, including in material filling and oil draining. Precautions across fire and explosion firmness be appropriate however, in unoccupied areas such as compressor houses and solo plant such as analytic stores where accumulations of vapour may go unnoticed.
PRECAUTIONS Con TOXIC RISK
Respiratory protective equipment
7 Any person entering an area in which ammonia vapour is expected to be present at a extraordinary level (eg for get back or fault-finding purposes) prerequisite wear self-contained or air service breathing apparatus. This does not include routine visits to plant rooms etc. A ample and properly maintained set should be conveniently sited adjacent to, but outside, exclusive area in which raised levels of .ammonia vapour potency arise. In no terms should anyone enter an range where a flammable absorption of gas may be present. Circumstances of suitable apparatus are contained in File 2501 "Certificate of Consent (Breathing Apparatus)," published annually by HSE. See likewise Guidance Note GS 5 as regards entry into confined spaces.
8 Ample respiratory protective equipment requisite be worn by every character carrying out engineering preservation work on any development where there is a disclosure of release of ammonia. Full face canister respirators with type A (blue) canisters according good protection in atmospheres up to 2% absorption or 20,000 ppm, since one hour. Work in alike a concentration is expected to lead to pain quickly due to fur irritation as ammonia dissolves in perspiration. A list of suitable accessory is given in file 2502 "Certificate of Blessing (Canister Gas Respirators)". Since substantial jobs impervious suits may be basic if the gas cannot be cleared.
9 Everybody who is likely to commitment to use respiratory protective device must be properly old-time in its use and requisite be fully aware of its limitations. The device must be maintained, kept clean and examined at least once a month. Convenient records should be kept. If canister respirators are used there must be an operating system for deciding when the canisters should be renewed.
Evacuation and exposure procedures
10 lt is basic that a clear exposure procedure is drawn up which circumstances the precise duties of everybody staff and the arrangements by reason of evacuation, rescue, first aid, deposit isolation etc. It is frequently important that evacuation procedures are clearly set out and ever practised where refrigeration systems are in busy areas. A common education which may be ample is to use the bonfire alarm provided that actuating points are instantly available at working areas. Personnel should be warned not to approach any vapour clouds. (Clouds may everyday look like steam as of the cooling of the released gas).
11 Apt exits should be maintained from entomb rooms at, all times. Crew seriously affected by an ammonia avert suffer streaming eyes and cruel coughing and rapidly grow into disorientated. They therefore require clear prior knowledge of a safe exit route.
Training in bury operation and maintenance
12 Anyone personnel involved in the deal and maintenance of the bury must be adequately trained. The training should cover not only general principles of refrigeration nonetheless also specific points related to the particular plant. A certain applies as much to care contractors as to an employer's acquiesce staff.
PLANT LOCATION
Plant not designed as outdoor location
13 In the employment of standard refrigeration bury (ie plant not chiefly designed for outdoor location) danger to excessively low condition temperatures may cause liquefaction of ammonia in reach the compressor leading to compressor damage, which could be hazardous. A certain type of plant should so be sited in a compressor building using the precautions described in BS 4434:1980 and outlined below. Compressor-houses should, where reasonably practicable, be fitted amidst explosion relief (eg by using cipher fragile roof). Where loosely held panels are hand-me-down as explosion relief, they should be suitably mute (eg by chains) to bar them becoming dangerous missiles in the case of an explosion.
14 ln direction to facilitate the accouterment of ventilation and boom relief, compressor-houses should couple at least one foreign wall. The siting of compressors in confined areas, basements, etc should be avoided anyplace practicable. Doors between entomb rooms or compressor-houses and added parts of the construction should be self-closing and well-fitting.
Plant designed since outdoor location
15 Only deposit specifically designed for the temperature should be installed outdoors. Alike installations should be sited in a protected position in the disclose air with, if necessary, weather preservation using a Dutch barn type structure which has an evenly distributed gutter open area equivalent to at gutter 50% of the account wall area.
Plant in workrooms
16 As a ongoing principle the amount of entomb containing ammonia situated in workrooms and increased populated areas should be minimised. Added plant such as flood drums and liquid pumps should everywhere possible be sited overseas from working areas. Compressors are constantly noisy and this is alternative reason for not having authority in working areas.
Ventilation
17 Compress or houses should be provided along adequate and suitable ventilation to accost the following requirements:
(1) Mundane Ventilation Sufficient permanent ventilation should be provided to avoid build up of toxic concentrations of ammonia from operational flood (eg from seals, glands etc). It is apparent that the redrafted British Typical will insist on industrial car ventilation rather than bet on rather uncertain natural ventilation.
(2) Emergency ventilation Accouterment should be made as sufficient mechanical ventilation to prevent flammable ammonia/air mixtures growing in the event of moderately foreseeable plant or operational drop (eg valve failure). In aforesaid circumstances the aim should be to conduct concentrations below 25% of the junior explosive limit (ie 4%).
18 The ventilation requirements as a particular installation courage depend on the type, capacity, operating conditions and location of the bury and may require creature assessment by a ventilation builder with appropriate expertise. However, the back general points apply:
(1) permanent natural or mechanical ventilation, or a alliance of both, may be used for normal or emergency ventilation. Mechanical ventilation initiated by ammunition detectors or manually (in the affair of continuously manned plants) may again be used for crisis ventilation (see para 26); and Appendix 3 as electrical safety of the system;
(2) the ventilation should emission to a safe place in the open air;
(3) in since the ventilation to be provided, the possible effects of cold on entomb should be taken into detail (see para 12);
(4) discharge of air through cracks viable windows, doors etc, or the entry of windows or doors should not be relied on after all ventilation;
(5) the formulae in BS4434 by reason of quantifying ventilation requirements are rules of claw based on unstated assumptions (eg they accept no account of foyer size or leak rates). Inspectors should caution that the formulae may be worn as a basic attend but discretion in their accurate application to a material plant should be stressed. A particular is particularly important along very large systems albeit the ventilation required by the formulae becomes impracticable; and
(6) it should be famous that the standard of ventilation disposed by the formulae in BS 4434: 1980 is not intended to activity with prolonged releases from main plant failure. However, the latter is very unlikely to exist in properly designed, constructed and maintained plant. Agency of sources of ignition and deposit shutdown (see paras 22-26) should further provide protection in aforesaid circumstances. Manually operated controls by reason of emergency ventilation should be located in a safe, definitely accessible place along amidst the control or switch for turning off the compressor.
Plant integrity
19 There can be serious corrosion of the horizontal pressure. parts of pipework and deposit due to condensation. It bag progress unnoticed under lagging which is not absolutely vapour sealed and is mostly rapid on plants which tour intermittently and pass-through OoC. The ongoing principles relating to the preservation of pressure systems are appropriate. The manufacture should be thoroughly examined by a able person at regular intervals in accordance amidst a written scheme. Attendant should be an active maintenance scheme.
Pipework
20 All parts of refrigerating systems and in concrete pipework should be positioned or safe to minimise the liability of impact damage, as example by fork drive trucks. Pipework and valves should be certainly marked to indicate their contents and function.
Oil consume system
21 Many of the reported incidents involving ammonia refrigeration systems accept been the result of a malfunction of the oil drain system (designed to visit the "carry-over" of margarine from the compressors). In almost cases oil is bored from below liquid ammonia and is saturated amidst it. In addition the oil is viscous because it is cold. In duty to minimise the hazard of escape from a well known cause the following measures should be advised:
(1) point short distances are absorbed and adequate observation of the absorb is possible oil deplete pipes should terminate in a protected location in the expose air. Valves on all pipe extension should not accept the possibility of liquid ammonia as a result of trapped; a bleed valve or hydrostatic relief valve venting to a safe place should be provided in the sections betwixt valves, as appropriate;
(2) a double valve arrangement should be provided at butter drains. In addition to the operational brochure valve, there should be an self closing spring or weight-loaded valve; and
(3) The need of oil drain catchpots. These are a appropriate feature on new plant, however existing plant cannot generally be easily modified. Before the oil is drained, the catchpot is distant from the liquid ammonia/oil feedline and the catchpot is electrically angry to boil off exclusive ammonia which flows as a vapour to the flat pressure side of the system. At the catchpot is warm, it is likewise isolated on the vapour page and the oil is before drained from it.
Ammonia filling point
22 Ammonia filling points should be located in safe, properly ventilated positions and, point reasonably practicable, in the expose air. Filling points should be sited abroad from sources of ignition.
PRECAUTIONS Against FIRE AND EXPLOSION RISK
Sources of ignition
23 Anybody likely sources of ignition (naked flames etc) should be eliminated from compressor houses and from the urgent vicinity of externally located plant.
Electrical equipment
24 Consultation on electrical apparatus after all use in potentially device atmospheres is given in RS 5345: Design 1: 1976 "Code of Background for the Selection, Airport and Maintenance of Electric Apparatus for Use in Potentially Bomb Atmospheres, Part 1, Basic Requirements for all Parts of the Code"; BS 4434: 1980, Portion 13 "Electrical Installations". The approaches followed by the raised documents differ.
25 As a current principle, electrical equipment should be sited away the compressor room in a intact location. However, when it is approximately sited in the room, it should be in accordance with the guidance given in para 27.
26 Where the ammonia compressors and refrigeration entomb are located in the same room as the endowment switch gear for the-premises deportation would probably be inconvenient and costly. In aforesaid cases, Field Consultant Division (FCG) advise on the approximately suitable safety precautions in the concrete case should be sought.
Electrical accessory selection criteria
27 The obligation of electrical apparatus in refrigeration plants using ammonia has been expressed a special case because of the flammability characteristics of the food (high LEL and finite explosive range) and the element that it can be detected at actually low levels by smell. A particular has resulted in a home of options which may be expressed when selecting electrical device for ammonia plants and these are clear in Appendix 3.
OTHER RISKS
28 Refrigeration systems everyday have associated risks which may desire attention, These include the exposure of trapping in clinical stores and chills, the handling of very cold products and microbiological problems corporate with cooling towers worn for the condenser.
ENFORCEMENT APPROACH
29 Imposition officers should advise a certain ammonia refrigeration plant should adapt with the guidance in BS 4434: 1980 as amended and positive by the information in a well known circular. They should once bear in mind:
(1) ammonia presents a toxic disclosure at concentrations far below those at which it presents each fire or explosion risk. Attendant have been 2 gassing fatalities betwixt 1977 and 1983 in the UK nonetheless only 3 incentive ammonia/air explosions in the basic 20 years;
(2) the likely consequences of an case in terms of impairment to personnel, and the current public should be assessed;
(3) BS4434 was first published in 1969 and was not intended to be retrospective, despite improvements in installations which pre-date the simple should be recommended, location reasonably practicable;
(4) analysis of the l983 visits energetically suggest that where reliant conditions of the plant are found there is everyday inadequate attention to withdrawal and emergency action; and
(5) point enforcement officers encounter care contractors they should cause enquiries about their active practices and training.
Further advice
30 A certain is a complicated industrialized subject and there are muscular trade pressure groups. Administration officers are recommended to pursue the advice of HSEs Field Consultant Group (FCG) via the Governmental Enforcement Liaison Officer (ELO), before considering enforcement action.
________________________________________
Ammonia is used as a refrigerant because of particular thermodynamic properties which implement it to move heat far more efficiently than increased refrigerant gases such as halogenated hydrocarbons. It is frequently suited to working in the area approximately OoC to -30oC and accordingly is widely used by reason of food preservation, the chilling of liquids akin as milk, beer and peaceful drinks, and in the chemical industry. New systems endure to be installed.
2. A typical system theoretically needs 4 components:
(1) evaporator;
(2) compressor;
(3) condenser; and
(4) reducing valve
In background other components such as margarine separator, intercooler, liquid receiver, flow drum and liquid pumps are daily found.
3 The useful refrigeration is produced at the evaporator. Liquid ammonia at flat pressure, and hence horizontal temperature, takes in bake by vaporising. This vapour is removed by the compressor which, in compressing it, raises the temperature from below to above ambient. The hot compressed electricity gives up the melt by condensing to a liquid in the condenser. The over pressure liquid then passes complete the pressure reducing valve to the evaporator. At the valve the liquid is cooled as some vapour flashes off. The remaining liquid is available after all use in the evaporator.
4 In a businesslike system it is expected there will be additional items of plant. An shortening separator removes suspended margarine carried over from the compressor and either returns it to the (pressurised) crank-case or holds it after all draining in some way. Ready may be a multi-stage compressor along an intercooler. This is cooled by agonized high pressure liquid into the horizontal pressure side.
Downstream of the condenser is approximately a liquid receiver. Ensuing of the reducing valve is day-to-day found a surge barrel which acts as a basin of cold liquid and evens down demand on the compressor and condenser. The liquid ammonia is drawn from the flow drum by a pump. Oil drains may be create on surge drums, liquid receivers, and away on large plants. Attendant is also likely to be an automatic control system on anybody but the oldest and smallest plants.
A simple practical refrigeration system
1 The aim was to collect consultation about a cross brick of installations. One hundred and forty eight returns were used in the analysis which recycled the Edinburgh FCG microcomputer.
2 Returns covered a clear range of processes in the food and drinks industries. The greater single sector was dairying (chilled h2o supply) with substantial returns likewise from frozen food producers and analytic stores. In the drinks region cooling and soft drinks carbonators were the main uses.
There were a open range of other uses reported; almost parts of the bread industry require controlled temperatures below ambient at some article of their process. A free range of sizes of installations from 45 kg to 45 tonne chargeweight were reported, 13% were over 5 tonnes, 40% 'tween 1 and 5 tonnes, 35% amid 100kg and 1 tonne and 12% 1 00 kg or below.
The oldest composing reported was pre-war and attendant was a fairly alike spread of age from 1960 to the present.
3 Eighty-nine per cent of installations had a nonpartisan compressor room. Forty-nine fee had the system charging grade in the compressor hall and 38% had it outdoors. Twenty-seven per cent of the sample could positively be identified as having doors to the outside of the building only. Thirty-six per cent of the additional compressor rooms did not conclude self-closing doors and 17% did not admit well-fitting doors. With compressors in a nonpartisan room this is a exceptionally large number where constant the most rudimentary precautions to bar the spread of escaping electricity has not been taken. Fifty-five per cent had condensers mounted above ground level outside - commonly on the roof. This raises questions of protected access and also avert in the event of an emergency.
4 Thirty-six percent, had the evaporator in the workroom. (These were ever product freezers in the frozen cuisine sector and carbonators at the reticent drinks plants). This points to the engagement for effective emergency procedures in the affair of leakage, particularly if it is in the workroom.
5 Unattended 3% of installations were identified as having pipework or entomb capable of being damaged by, after all example, fork lift trucks. Half of the entire ballot however had unmarked pipework. (Notes of alive with proformas suggested that a particular would receive early attention).
6 lt proved absurd to carryout meaningful investigation of the ventilation provided in compressor rooms. A average installation seemed to rely largely on natural ventilation (perhaps assisted by a limited fan) for normal ventilation. Location there was provision of ventilation notably for emergencies, it tended to be a self-reliant system rather than a 2 agility fan on the everyday ventilating system. Only 23% of the installations had 2 ventilation rates applicable and only half the ventilation systems of all kind could be experimental from outside the compressor room. Solo half of these ventilation systems were automatically controlled.
7 Only 16% of anyone system charging was done by a character on his own; the typical arrangement was 2 men. Shortening draining was done by anybody man on his acquiesce at 30% of everybody Installations. At 51 % of everybody installations it was carried away more than once a month. Unattended 26% of installations had spring-loaded valves or a catchpot construction at oil drains. Approximately of the rest had hardly a short stub of cylinder from a vessel containing liquid ammonia halcyon by a single valve. In 71 % of cases point the oil drain was unsatisfactory inspectors expressed that the reasonably practicable alteration was the fitting of self-closing valves. The 30% of installations point one man did the margarine draining on his avow included 6 which had no respirator of any kind.
8 Forty-two per cent of compressor houses had no electricity detectors. Sieger was by deep the most common supplier (60%) of everybody detection systems. The about common service period of twice per year reflects a well known company's normal service contract. Nineteen per cent of detector systems were don't hold your breath checked.
Approximately half of the detector installations alone had one operating level. Twenty-seven per cent of systems did not shut down the plant however merely raised the alarm. Ten per cent of the systems had no independent alarm.
9 Sixty-six percent of compressor entrance electrical installations were not absolutely equipped to Zone 2 classic even where much of the plant was under the agency of detectors. Seventy-five per cent of everybody compressor installations could be switched away elsewhere outside the compressor gallery (even if only at the essential supply). Of the remainder, the basic switchgear was either in the compressor foyer or access to it was over the compressor room.
10 Eighty-eight bonus of all sites had 2 or likewise sets of respiratory insurance of some kind. Six installations (4%) had none at all. At 83% of sites ready was said to be some sort of training in the need of respiratory protection nonetheless only 43% had some character of systematic examination. At unattended 5 installations (3.4%) were near possible limitations of operation which conflicted with accouterment of respiratory protection and the essential problem seemed to be access up ladders or alive congested items of plant.
11 Forty-seven per cent of sites had reviving appliance available usually for current first aid rather than exclusively because of the ammonia.
12 Twenty-seven chunk of sites had Draeger (or similar) detector tubes after all measuring low concentrations of ammonia. Many others had sulphur sticks or hydrochloric acerbic for detecting small leaks.
13 Fifty-nine fee of installations were maintained at first partly by contractors. Apart from a few central suppliers and installers of device there were many civilian refrigeration engineers who solo appeared once or twice in the survey. No consultation is available about the usual of training or workmanship of these contractors.
14 Fifty-five percentage of all sites appeared to believe emergency evacuation procedures (43% hand-me-down the fire alarm) although slightly fewer (50%) appeared to confer any training in these procedures. Unattended 24% appeared to conclude detailed rescue arrangements. Twenty-two per cent had written systems of trade which appeared comprehensive and alone 34% had what appeared to be alive plant operator training.
________________________________________
APPENDIX 3 (paras 1 and 26)
PROTECTION OF Electrical APPARATUS AT AMMONIA COMPRESSORS AND REFRIGERATION PLANT
EXTERNALLY SITED PLANT
1 Compressors and refrigeration plant sited in out gate locations in accordance along para 14 of a well known Circular in otherwise non-hazardous areas firmness not normally require chiefly protected electrical equipment.
INTERNALLY SITED PLANT
2 A leakage chart of the basic requirements relating to the magnetic apparatus for internally sited deposit is given in the supplement to that appendix. The operational approaches are given below.
Option 1 - Need of explosion protected electrical apparatus
3 Hazardous area classification should be carried away by a competent person. Ac apparatus should then be preferred in accordance with BS 5345: Detail 1: 1976 Section 2. The max of compressor-houses should be regarded as Part 2 areas. Type "N" barrage protected equipment (including any emergency ventilation fans) courage be suitable for these locations.
Option 2 - Diagnosis of leaks by group or gas detectors
4 ln a certain approach, non-explosion protected electrical apparatus, with qualifications, may be used in combination with a readily available means of isolating the ac supply. The method of achieving the recent can be accomplished either no doubt after detection of a flood by a gas detector system, or manually afterwards a leakage has been detected by personnel. The need of these techniques as a advance line of defence is half to applications solely involving ammonia in refrigeration plants. A particular approach is considered competent provided that the modern principles outlined in paras 10-17 are followed and a particular sufficient account is taken of paras 5-9.
Gas detectors
5 The detectors should be suitably positioned taking into history the physical characteristics of the deposit room, the pattern of airflow action in it and the almost likely sources of likely leakage. Due regard should be paid to all dead pockets or recesses. Feat has shown that, in actual circumstances, it is apparent for cold ammonia vapour to stratify initially at flat levels. Unless the occupier has apt expertise within his acquiesce organisation, it would be advisable as him to consult a corporation which specialises in the composition and installation of food detection systems.
6 As a rough guide only, one might expect to see detectors in the vicinity of the compressors and increased non-static items of deposit and at ceiling classification where one detector per 36M2 of plaster area would probably be sufficient, albeit more may be essential if there are broad beams creating recesses. The detailed is to ensure a well known the ammonia is detected and the apparatus rendered safe before flammable concentrations enter a source of ignition. (This objective, which is further applicable to "detection" of a leak by personnel, is mostly critical with regard to electrical apparatus which is not chiefly designed to be non-sparking, non explosion-protected electric apparatus and electrical device with temperatures above 630'C).
7 The detectors should be suitably boom protected.
8 The detectors worn are of the "pellistor" category and may be subject to poisoning by airborne contaminants. They should then be properly installed and maintained and constantly checked. The operation of the detectors should be limited using standard ammonia fuel mixtures. Certain V-belt dressings containing antimony conclude been shown to medicine detectors and gradually curtail their response.
9 The detectors should be able of detecting concentrations of ammonia at 1 % v/v or less.
Associated magnetic apparatus
10 Account should be taken of the electric control system circuitry and the acute possible degree of decline to safety should be achieved, so buried as is reasonably practicable. Present guidance is contained in BS 5304: 1975 "Safeguarding of Machinery" Block 6.
11 The isolating device(s), whether manually or naturally operated, which cuts abroad the electricity supply to the ammonia plant room, should be located in a non-hazardous area. It bottle be either a maker or circuit breaker. If the criteria in paras 5-9 raised have been satisfied, the back recommendations in paras 13-17 should be adopted. (Although definite specific details have been taken from BS 4434:1980, by access of example, they are intended to identify the general principles of a particular approach and not distinct requirements -which will have, to be dangerous in each particular case).
12 Mind will need to be paid to the control of other circuits which accept the plant room and are not directly associated with the plant, eg socket outlets by reason of portable tools.
Continuously manned rooms
13 Privacy of all electrical circuits should be effected by isolating devices located in a non-hazardous area. These devices should be objective by push buttons instantly outside the plant room, or experimental by a gas diagnosis system as described pare 14, and arranged to according visual and audible alarms to reversal on equipment for crisis ventilation and/or emergency lighting (if installed). All electrical apparatus that is required to apply in the room after a leakage has been detected, akin as ventilation equipment and emergency lighting, should be suitably protected for the hazardous field in which it is sited, ie District 2. Few compressor rooms are deliberately manned. Detection of discharge by operators is solo reliable if they are deliberately present in the room. If by reason of example they have added duties, or leave the field for meals etc, or demand an isolated noise refuge earlier the speed of feeling is likely to be actually slower than that of ascetic detectors.
Unmanned plant rooms
14 lsolation of anyone electrical circuits should be effected by isolating devices located in a non-hazardous range and controlled by all or more suitable ammonia fuel detectors which should likewise be arranged to confer a visual and noticeable alarm and to switch on equipment for ventilation and/or exposure lighting, if installed. The ventilation facet should be discharged to the elsewhere of the building in akin a manner as not to cause distress or danger to persons in the vicinity of the building. Round isolation should be effected at ammonia concentrations below 25% LEL and an bell setting of 1.5% v/v followed by band isolation at 3% v/v is suggested.
15 Care personnel are required to enter unmanned plant rooms and adept means of escape should be provided.
16 Human protection including breathing apparatus, and ostensibly impervious suits, may be needed in all room or space if maintenance men are likely to consume pipework or do all other operation liable to call liquid ammonia or physical quantities of gas. 19014 19015 19016 19017 19018 19019 19020 19021 19022 19023 19024 19025 19026 19027 19028 19029 19030 19031 19032 19033 19034 19035 19036 19037 19038 19039 19040 19041 19042 19043 19044 19045 19046 19047 19048 19049 19050 19051 19052 19053 19054 19055 19056 19057 19058 19059 19060 19061 19062 19063 19064 19065 19066 19067 19068 19069 19070 19071 19072 19073 19074 19075 19076 19077 19078 19079 19080 19081 19082 19083 19084 19085 19086 19087 19088 19089 19090 19091 19092 19093 19094 19095 19096 19097 19098 19099 19100 19101 19102 19103 19104 19105 19106 19107 19108 19109 19110 19111 19112 19113 19114 19115 19116 19117 19118 19119 19120 19121 19122 19123 19124 19125 19126 19127 19128 19129 19130 19131 19132 19133 19134 19135 19136 19137 19138 19139 19140 19141 19142 19143 19144 19145 19146 19147 19148 19149 19150 19151 19152 19153 19154 19155 19156 19157 19158 19159 19160 19161 19162 19163 19164 19165 19166 19167 19168 19169 19170 19171 19172 19173 19174 19175 19176 19177 19178 19179 19180 19181 19182 19183 19184 19185 19186 19187 19188 19189 19190 19191 19192 19193 19194 19195 19196 19197 19198 19199 19200 19201 19202 19203 19204 19205 19206 19207 19208 19209 19210 19211 19212 19213 19214 19215 19216 19217 19218 19219 19220 19221 19222 19223 19224 19225 19226 19227 19228 19229 19230 19231 19232 19233 19234 19235 19236 19237 19238 19239 19240 19241 19242 19243 19244 19245 19246 19247 19248 19249 19250 19251 19252 19253 19254 19255 19256 19257 19258 19259 19260 19261 19262 19263 19264 19265 19266 19267 19268 19269 19270 19271 19272 19273 19274 19275 19276 19277 19278 19279 19280 19281 19282 19283 19284 19285 19286 19287 19288 19289 19290 19291 19292 19293 19294 19295 19296 19297 19298 19299 19300 19301 19302 19303 19304 19305 19306 19307 19308 19309 19310 19311 19312 19313 19314 19315 19316 19317 19318 19319 19320 19321 19322 19323 19324 19325 19326 19327 19328 19329 19330 19331 19332 19333 19334 19335 19336 19337 19338 19339 19340 19341 19342 19343 19344 19345 19346 19347 19348 19349 19350 19351 19352 19353 19354 19355 19356 19357 19358 19359 19360 19361 19362 19363 19364 19365 19366 19367 19368 19369 19370 19371 19372 19373 19374 19375 19376 19377 19378 19379 19380 19381 19382 19383 19384 19385 19386 19387 19388 19389 19390 19391 19392 19393 19394 19395 19396 19397 19398 19399 19400 19401 19402 19403 19404 19405 19406 19407 19408 19409 19410 19411 19412 19413 19414 19415 19416 19417 19418 19419 19420 19421 19422 19423 19424 19425 19426 19427 19428 19429 19430 19431 19432 19433 19434 19435 19436 19437 19438 19439 19440 19441 19442 19443 19444 19445 19446 19447 19448 19449 19450 19451 19452 19453 19454 19455 19456 19457 19458 19459 19460 19461 19462 19463 19464 19465 19466 19467 19468 19469 19470 19471 19472 19473 19474 19475 19476 19477 19478 19479 19480 19481 19482 19483 19484 19485 19486 19487 19488 19489 19490 19491 19492 19493 19494 19495 19496 19497 19498 19499 19500 19501 19502 19503 19504 19505 19506 19507 19508 19509 19510 19511 19512 19513 19514 19515 19516 19517 19518 19519 19520 19521 19522 19523 19524 19525 19526 19527 19528 19529 19530 19531 19532 19533 19534 19535 19536 19537 19538 19539 19540 19541 19542 19543 19544 19545 19546 19547 19548 19549 19550 19551 19552 19553 19554 19555 19556 19557 19558 19559 19560 19561 19562 19563 19564 19565 19566 19567 19568 19569 19570 19571 19572 19573 19574 19575 19576 19577 19578 19579 19580 19581 19582 19583 19584 19585 19586 19587 19588 19589 19590 19591 19592 19593 19594 19595 19596 19597 19598 19599 19600 19601 19602 19603 19604 19605 19606 19607 19608 19609 19610 19611 19612 19613 19614 19615 19616 19617 19618 19619 19620 19621 19622 19623 19624 19625 19626 19627 19628 19629 19630 19631 19632 19633 19634 19635 19636 19637 19638 19639 19640 19641 19642 19643 19644 19645 19646 19647 19648 19649 19650 19651 19652 19653 19654 19655 19656 19657 19658 19659 19660 19661 19662 19663 19664 19665 19666 19667 19668 19669 19670 19671 19672 19673 19674 19675 19676 19677 19678 19679 19680 19681 19682 19683 19684 19685 19686 19687 19688 19689 19690 19691 19692 19693 19694 19695 19696 19697 19698 19699 19700 19701 19702 19703 19704 19705 19706 19707 19708 19709 19710 19711 19712 19713 19714 19715 19716 19717 19718 19719 19720 19721 19722 19723 19724 19725 19726 19727 19728 19729 19730 19731 19732 19733 19734 19735 19736 19737 19738 19739 19740 19741 19742 19743 19744 19745 19746 19747 19748 19749 19750 19751 19752 19753 19754 19755 19756 19757 19758 19759 19760 19761 19762 19763 19764 19765 19766 19767 19768 19769 19770 19771 19772 19773 19774 19775 19776 19777 19778 19779 19780 19781 19782 19783 19784 19785 19786 19787 19788 19789 19790 19791 19792 19793 19794 19795 19796 19797 19798 19799 19800 19801 19802 19803 19804 19805 19806 19807 19808 19809 19810 19811 19812 19813 19814 19815 19816 19817 19818 19819 19820 19821 19822 19823 19824 19825 19826 19827 19828 19829 19830 19831 19832 19833 19834 19835 19836 19837 19838 19839 19840 19841 19842 19843 19844 19845 19846 19847 19848 19849 19850 19851 19852 19853 19854 19855 19856 19857 19858 19859 19860 19861 19862 19863 19864 19865 19866 19867 19868 19869 19870 19871 19872 19873 19874 19875 19876 19877 19878 19879 19880 19881 19882 19883 19884 19885 19886 19887 19888 19889 19890 19891 19892 19893 19894 19895 19896 19897 19898 19899 19900 19901 19902 19903 19904 19905 19906 19907 19908 19909 19910 19911 19912 19913 19914 19915 19916 19917 19918 19919 19920 19921 19922 19923 19924 19925 19926 19927 19928 19929 19930 19931 19932 19933 19934 19935 19936 19937 19938 19939 19940 19941 19942 19943 19944 19945 19946 19947 19948 19949 19950 19951 19952 19953 19954 19955 19956 19957 19958 19959 19960 19961 19962 19963 19964 19965 19966 19967 19968 19969 19970 19971 19972 19973 19974 19975 19976 19977 19978 19979 19980 19981 19982 19983 19984 19985 19986 19987 19988 19989 19990 19991 19992 19993 19994 19995 19996 19997 19998 19999 20000 20001 20002 20003 20004 20005 20006 20007 20008 20009 20010 20011 20012 20013
