AMMONIA COMPRESSORS AND REFRIGERATION Entomb From Jambi

by JABS newsindo-27 June 21, 2023

INTRODUCTION

1 A certain circular gives advice on the precautions to be taken against the toxic, fire and bang hazards presented by refrigeration systems containing ammonia. These are approximately likely to be commence by LA enforcement officers at clinical stores and food delivery warehouses. It applies to the entire system not simply the compressor house. It provides limited advice on matters of apprehension to enforcement officers pending check of BS 4434:1980.

2 Appendix 1 outlines the current principles of refrigeration, Appendix 2 gives encouragement on the results of the programme of appropriate visits carried out in 1983 by Cooperative Inspectorate (F1) to deal with present standards in the cooking industry and Appendix 3 gives careful guidance on electrical standards. Enforcement officers should not overemphasise the hazards of ammonia compared alongside other refrigerants.

HAZARDS

Toxicity

3 Ammonia is a chemically reactive electricity that is very soluble in rain and is much lighter than attitude (vapour density 0.59 of a particular of air). Cold vapour (e.g. from leaks) may ever be denser than air. Despite there have been incidents of crisis to harmful concentrations of ammonia in the UK there have been few alarming accidents. Ammonia is characterised by a classic pungent odour and is detectable by most people at levels of about 50 ppm in the atmosphere. Although workers become tolerant to a particular effect and in the yesterday have been able to business without distress at levels up to 70 ppm, currently the recommended exposure dimension for ammonia is 25 ppm, 8 day TWA (0.0025%) and the cross term exposure limit is 35 ppm, 10 little TWA. At 400 ppm, about people experience immediate adenoids and throat irritation, however suffer no permanent ill-effects subsequently 30-60 minute exposure. A category of 700 ppm causes immediate irritation to the eyes, and a category of 1,700 ppm (0.17%) boldness give rise to continuing coughing and can be bad after about 30 minutes exposure.

Exposure to concentrations improved 5,000 ppm (0.5%) after all quite short periods container result in death. Feeling to the effects of ammonia varies widely amid individuals, and the dose-response effects described over are likely to be those deft by the more free members of the population.

Fire and explosion

4 Ammonia forms a flammable blend with air at concentrations betwixt 16 and 25% v/v. Ready have however been actually few incentive explosions involving ammonia compressor houses in the UK and everybody of the reported incidents attentive ammonia leakage from deposit under maintenance.

Existing guidance

5 Contemporary guidance on the precautions which should be taken with ammonia refrigeration plant may be commence in: British Standard 4434: 1980 "Requirements after all Refrigeration Safety: Part 1, General". The requirements (particularly from the f ire and barrage standpoint) are similar to those in the forward (1 969) version. Anyway a' full revision of BS 4434 is taking place.

Precautions

6 Under normal circumstances people courage not be able to allow ammonia concentrations at balanced a fraction of the flammable limit. The convenient precautions are mainly those apt against toxic effects in occupied areas and to employment where sudden exposures are foreseeable, akin as maintenance and fitness work, including in material filling and oil draining. Precautions adjacent fire and explosion courage be appropriate however, in unoccupied areas aforesaid as compressor houses and alone plant such as clinical stores where accumulations of vapour may go unnoticed.

PRECAUTIONS Adjacent TOXIC RISK

Respiratory protective equipment

7 Each person entering an field in which ammonia vapour is likely to be present at a famous level (eg for recover or fault-finding purposes) precondition wear self-contained or airline breathing apparatus. This does not add routine visits to deposit rooms etc. A adequate and properly maintained team should be conveniently sited adjacent to, but outside, exclusive area in which over levels of .ammonia vapour might arise. In no conclusion should anyone enter an range where a flammable combination of gas may be present. Charge of suitable apparatus are contained in File 2501 "Certificate of Confirmation (Breathing Apparatus)," published annually by HSE. See also Guidance Note GS 5 as regards entry into confined spaces.

8 Enough respiratory protective equipment prerequisite be worn by every customer carrying out engineering conservation work on any development where there is a disclosure of release of ammonia. Absolute face canister respirators along type A (blue) canisters bestow good protection in atmospheres up to 2% consolidation or 20,000 ppm, after all one hour. Work in aforesaid a concentration is fair to lead to agony quickly due to skin irritation as ammonia dissolves in perspiration. A list of suitable device is given in form 2502 "Certificate of Confirmation (Canister Gas Respirators)". Since substantial jobs impervious suits may be basic if the gas cannot be cleared.

9 Anyone who is likely to commitment to use respiratory protective appliance must be properly trained in its use and must be fully aware of its limitations. The apparatus must be maintained, kept bright and examined at first once a month. Apt records should be kept. If canister respirators are hand-me-down there must be an effective system for deciding when the canisters should be renewed.

Evacuation and exposure procedures

10 lt is essential that a clear exposure procedure is drawn up which terms the precise duties of anybody staff and the arrangements by reason of evacuation, rescue, first aid, plant isolation etc. It is frequently important that evacuation procedures are apparently set out and always practised where refrigeration systems are in active areas. A common control which may be abundant is to use the bonfire alarm provided that actuating points are immediately available at working areas. Cadre should be warned not to access any vapour clouds. (Clouds may constantly look like steam as a result of of the cooling of the released gas).

11 Apt exits should be maintained from deposit rooms at, all times. Personnel seriously affected by an ammonia avert suffer streaming eyes and violent coughing and rapidly grow into disorientated. They therefore require clear prior knowledge of a protected exit route.

Training in entomb operation and maintenance

12 Everyone personnel involved in the activity and maintenance of the entomb must be adequately trained. The discipline should cover not alone general principles of refrigeration however also specific points comparable to the particular plant. A certain applies as much to conservation contractors as to an employer's acquiesce staff.

PLANT LOCATION

Plant not designed by reason of outdoor location

13 In the event of standard refrigeration plant (ie plant not chiefly designed for outdoor location) emergency to excessively low aspect temperatures may cause liquefaction of ammonia in a period the compressor leading to compressor damage, which could be hazardous. A particular type of plant should accordingly be sited in a compressor construction using the precautions described in BS 4434:1980 and outlined below. Compressor-houses should, locus reasonably practicable, be fitted along explosion relief (eg by using nothing fragile roof). Where loosely held panels are used as explosion relief, they should be suitably silent (eg by chains) to bar them becoming dangerous missiles in the employment of an explosion.

14 ln duty to facilitate the provision of ventilation and barrage relief, compressor-houses should associate at least one external wall. The siting of compressors in sick areas, basements, etc should be avoided anywhere practicable. Doors between plant rooms or compressor-houses and increased parts of the construction should be self-closing and well-fitting.

Plant designed by reason of outdoor location

15 Only deposit specifically designed for the climate should be installed outdoors. Such installations should be sited in a protected position in the bring to light air with, if necessary, weather insurance using a Dutch barn type structure which has an evenly distributed gutter open area equivalent to at gutter 50% of the budget wall area.

Plant in workrooms

16 As a modern principle the amount of deposit containing ammonia situated in workrooms and added populated areas should be minimised. Extra plant such as flood drums and liquid pumps should anywhere 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 confront the following requirements:

(1) Frequent Ventilation Sufficient permanent ventilation should be provided to bar build up of toxic concentrations of ammonia from operational flow (eg from seals, glands etc). It is supposed that the redrafted British Classic will insist on modern car ventilation rather than bank on rather uncertain natural ventilation.

(2) Emergency ventilation Arrangement should be made by reason of sufficient mechanical ventilation to avoid flammable ammonia/air mixtures growing in the event of adequately foreseeable plant or operational decline (eg valve failure). In aforesaid circumstances the aim should be to control concentrations below 25% of the lower explosive limit (ie 4%).

18 The ventilation requirements as a particular installation courage depend on the type, capacity, alive conditions and location of the plant and may require critter assessment by a ventilation artist with appropriate expertise. However, the final general points apply:

(1) enduring natural or mechanical ventilation, or a affiliation of both, may be recycled for normal or danger ventilation. Mechanical ventilation initiated by ammunition detectors or manually (in the employment of continuously manned plants) may likewise be used for danger ventilation (see para 26); and Appendix 3 after all electrical safety of the system;

(2) the ventilation should emission to a safe job in the open air;

(3) in after all the ventilation to be provided, the hidden effects of cold on plant should be taken into explanation (see para 12);

(4) flood of air through cracks alive windows, doors etc, or the access of windows or doors should not be relied on by reason of ventilation;

(5) the formulae in BS4434 as quantifying ventilation requirements are rules of ring finger based on unstated assumptions (eg they obtain no account of gallery size or leak rates). Inspectors should caution that the formulae may be worn as a basic follow but discretion in their careful application to a detailed plant should be stressed. A particular is particularly important with very large systems when the ventilation required by the formulae becomes impracticable; and

(6) it should be leading that the standard of ventilation accustomed by the formulae in BS 4434: 1980 is not intended to activity with prolonged releases from main plant failure. However, the final is very unlikely to endure in properly designed, constructed and maintained plant. Agency of sources of ignition and deposit shutdown (see paras 22-26) should further provide protection in such circumstances. Manually operated controls as emergency ventilation should be located in a safe, absolutely accessible place along with the control or alteration for turning off the compressor.

Plant integrity

19 There can be serious corrosion of the horizontal pressure. parts of pipework and bury due to condensation. It container progress unnoticed under lagging which is not completely vapour sealed and is mostly rapid on plants which run intermittently and pass-through OoC. The ongoing principles relating to the preservation of pressure systems are appropriate. The plan should be thoroughly examined by a able person at regular intervals in accordance along a written scheme. Ready should be an effective maintenance scheme.

Pipework

20 All parts of refrigerating systems and in detailed pipework should be positioned or safe to minimise the disclosure of impact damage, after all example by fork drive trucks. Pipework and valves should be definitely marked to indicate their contents and function.

Oil absorb system

21 Many of the reported incidents involving ammonia refrigeration systems conclude been the result of a malfunction of the shortening drain system (designed to visit the "carry-over" of shortening from the compressors). In almost cases oil is bored from below liquid ammonia and is saturated with it. In addition the butter is viscous because it is cold. In duty to minimise the disclosure of escape from that cause the following measures should be advised:

(1) locus short distances are interested and adequate observation of the deplete is possible oil absorb pipes should terminate in a intact location in the expose air. Valves on any pipe extension should not enter the possibility of liquid ammonia as a result of trapped; a bleed valve or hydrostatic alleviation valve venting to a protected place should be provided in the sections betwixt valves, as appropriate;

(2) a double valve arrangement should be provided at margarine drains. In addition to the operational brochure valve, there should be an autogenous closing spring or weight-loaded valve; and

(3) The obligation of oil drain catchpots. These are a appropriate feature on new plant, still existing plant cannot generally be easily modified. Ahead the oil is drained, the catchpot is far from the liquid ammonia/oil feedline and the catchpot is electrically angry to boil off each ammonia which flows as a vapour to the horizontal pressure side of the system. Albeit the catchpot is warm, it is again 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, accurately ventilated positions and, locus reasonably practicable, in the bare air. Filling points should be sited elsewhere from sources of ignition.

PRECAUTIONS Con FIRE AND EXPLOSION RISK

Sources of ignition

23 Everybody 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 Advice on electrical apparatus since use in potentially explosive atmospheres is given in RS 5345: Detail 1: 1976 "Code of Education for the Selection, Airfield and Maintenance of Electric Apparatus for Use in Potentially Bomb Atmospheres, Part 1, Elemental Requirements for all Parts of the Code"; BS 4434: 1980, Clause 13 "Electrical Installations". The approaches followed by the raised documents differ.

25 As a modern principle, electrical equipment should be sited abroad the compressor room in a secure location. However, when it is essentially sited in the room, it should be in accordance along the guidance given in para 27.

26 Point the ammonia compressors and refrigeration bury are located in the same room as the capital switch gear for the-premises transfer would probably be inconvenient and costly. In aforesaid cases, Field Consultant Division (FCG) advise on the almost suitable safety precautions in the objective case should be sought.

Electrical accessory selection criteria

27 The demand of electrical apparatus in refrigeration plants using ammonia has been express a special case as long as of the flammability characteristics of the fuel (high LEL and narrow explosive range) and the detail that it can be detected at literally low levels by smell. A well known has resulted in a home of options which may be clear when selecting electrical appliance for ammonia plants and these are explicit in Appendix 3.

OTHER RISKS

28 Refrigeration systems constantly have associated risks which may crave attention, These include the exposure of trapping in scientific stores and chills, the handling of very cold products and microbiological problems corporate with cooling towers hand-me-down for the condenser.

ENFORCEMENT APPROACH

29 Imposition officers should advise a well known ammonia refrigeration plant should accommodate with the guidance in BS 4434: 1980 as amended and positive by the information in that circular. They should anyhow bear in mind:

(1) ammonia presents a toxic hazard at concentrations far below those at which it presents exclusive fire or explosion risk. Attendant have been 2 gassing fatalities betwixt 1977 and 1983 in the UK still only 3 incentive ammonia/air explosions in the base 20 years;

(2) the likely consequences of an case in terms of ailment to personnel, and the present public should be assessed;

(3) BS4434 was advance published in 1969 and was not intended to be retrospective, admitting improvements in installations which pre-date the simple should be recommended, locus reasonably practicable;

(4) analysis of the l983 visits strongly suggest that where defenseless conditions of the deposit are found there is daily inadequate attention to evacuation and emergency action; and

(5) locus enforcement officers encounter conservation contractors they should bring about enquiries about their active practices and training.

Further advice

30 That is a complicated industrial subject and there are energetic trade pressure groups. Administration officers are recommended to pursue the advice of HSEs Range Consultant Group (FCG) via the Domestic Enforcement Liaison Officer (ELO), before considering enforcement action.

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Ammonia is worn as a refrigerant as a result of of particular thermodynamic properties which facilitate it to move bake far more efficiently than added refrigerant gases such as halogenated hydrocarbons. It is chiefly suited to working in the area approximately OoC to -30oC and therefore is widely used after all food preservation, the chilling of liquids aforesaid as milk, beer and quiet drinks, and in the alchemical industry. New systems extend to be installed.

2. A classic system theoretically needs 4 components:

(1) evaporator;

(2) compressor;

(3) condenser; and

(4) reducing valve

In culture other components such as margarine separator, intercooler, liquid receiver, flood drum and liquid pumps are day-to-day found.

3 The useful refrigeration is produced at the evaporator. Liquid ammonia at empty pressure, and hence horizontal temperature, takes in heat by vaporising. This vapour is removed by the compressor which, in compressing it, raises the climate from below to high ambient. The hot compressed food gives up the simmer by condensing to a liquid in the condenser. The high pressure liquid then passes over the pressure reducing valve to the evaporator. At the valve the liquid is cooled as some vapour flashes off. The pausing liquid is available by reason of use in the evaporator.

4 In a down-to-earth system it is acceptable there will be added items of plant. An shortening separator removes suspended shortening carried over from the compressor and either returns it to the (pressurised) crank-case or holds it as draining in some way. Near may be a multi-stage compressor alongside an intercooler. This is cooled by aching high pressure liquid into the low pressure side.

Downstream of the condenser is relatively a liquid receiver. Later of the reducing valve is daily found a surge drum which acts as a lake of cold liquid and evens away demand on the compressor and condenser. The liquid ammonia is drawn from the flood drum by a pump. Oil drains may be do on surge drums, liquid receivers, and away on large plants. Attendant is also likely to be an autogenous control system on anyone but the oldest and smallest plants.

A simple practical refrigeration system

1 The design was to collect consultation about a cross brick of installations. One hundred and forty eight returns were hand-me-down in the analysis which hand-me-down the Edinburgh FCG microcomputer.

2 Returns covered a accessible range of processes in the cuisine and drinks industries. The most single sector was dairying (chilled rain supply) with substantial returns also from frozen food producers and impersonal stores. In the drinks sector cooling and soft drinks carbonators were the main uses.

There were a open range of other uses reported; around parts of the cooking industry require controlled temperatures below ambient at some element of their process. A free range of sizes of installations from 45 kg to 45 tonne chargeweight were reported, 13% were above 5 tonnes, 40% amid 1 and 5 tonnes, 35% betwixt 100kg and 1 tonne and 12% 1 00 kg or below.

The oldest basic reported was pre-war and there was a fairly even spread of age from 1960 to the present.

3 Eighty-nine per cent of installations had a autonomous compressor room. Forty-nine percentage had the system charging degree in the compressor gallery and 38% had it outdoors. Twenty-seven per cent of the case could positively be identified as having doors to the elsewhere of the building only. Thirty-six per cent of the further compressor rooms did not conclude self-closing doors and 17% did not conclude well-fitting doors. With compressors in a self-reliant room this is a notably large number where even the most rudimentary precautions to prevent the spread of escaping food has not been taken. Fifty-five per cent had condensers mounted high ground level outside - normally on the roof. This raises questions of safe access and also dodge in the event of an emergency.

4 Thirty-six percent, had the evaporator in the workroom. (These were constantly product freezers in the frozen food sector and carbonators at the muted drinks plants). This points to the commitment for effective emergency procedures in the event 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. Limited of the entire ballot however had unmarked pipework. (Notes of bounteous proformas suggested that a particular would receive early attention).

6 lt proved hopeless to carryout meaningful investigation of the ventilation provided in compressor rooms. A moderate installation seemed to await largely on natural ventilation (perhaps assisted by a cramped fan) for normal ventilation. Point there was provision of ventilation especially for emergencies, it tended to be a self-reliant system rather than a 2 momentum fan on the commonplace ventilating system. Only 23% of the installations had 2 ventilation rates accessible and only half the ventilation systems of any kind could be scientific from outside the compressor room. Unattended half of these ventilation systems were necessarily controlled.

7 Only 16% of everybody system charging was done by a body on his own; the classic arrangement was 2 men. Margarine draining was done by everybody man on his acquiesce at 30% of everybody Installations. At 51 % of everyone installations it was carried down more than once a month. Solo 26% of installations had spring-loaded valves or a catchpot development at oil drains. Almost of the rest had barely a short stub of barrel from a vessel containing liquid ammonia halcyon by a single valve. In 71 % of cases locus the oil drain was unsatisfactory inspectors express that the reasonably practicable adjustment was the fitting of self-closing valves. The 30% of installations location one man did the shortening draining on his grant included 6 which had no respirator of any kind.

8 Forty-two per cent of compressor houses had no electricity detectors. Sieger was by broad the most common supplier (60%) of everyone detection systems. The almost common service period of twice per year reflects that company's normal service contract. Nineteen per cent of detector systems were forget it checked.

Approximately half of the detector installations only had one operating level. Twenty-seven per cent of systems did not push down the plant still merely raised the alarm. Ten per cent of the systems had no independent alarm.

9 Sixty-six percent of compressor hall electrical installations were not altogether equipped to Zone 2 usual even where much of the plant was under the agency of detectors. Seventy-five per cent of anybody compressor installations could be switched aside elsewhere outside the compressor gallery (even if only at the basic supply). Of the remainder, the key switchgear was either in the compressor foyer or access to it was buttoned up the compressor room.

10 Eighty-eight percentage of all sites had 2 or further sets of respiratory insurance of some kind. Six installations (4%) had nobody at all. At 83% of sites there was said to be some character of training in the need of respiratory protection however only 43% had some character of systematic examination. At solo 5 installations (3.4%) were ready possible limitations of area which conflicted with accouterment of respiratory protection and the key problem seemed to be approach up ladders or viable congested items of plant.

11 Forty-seven per cent of sites had reviving accessory available usually for present first aid rather than exclusively because of the ammonia.

12 Twenty-seven percentage of sites had Draeger (or similar) detector tubes since measuring low concentrations of ammonia. Many others had sulphur sticks or hydrochloric acid for detecting small leaks.

13 Fifty-nine fee of installations were maintained at bottom partly by contractors. Alone from a few central suppliers and installers of appliance there were many civilian refrigeration engineers who only appeared once or twice in the survey. No consultation is available about the typical of training or workmanship of these contractors.

14 Fifty-five percentage of all sites appeared to believe emergency evacuation procedures (43% used the fire alarm) nonetheless slightly fewer (50%) appeared to bestow any training in these procedures. Unattended 24% appeared to conclude detailed rescue arrangements. Twenty-two per cent had written systems of field which appeared comprehensive and unattended 34% had what appeared to be alive plant operator training.

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APPENDIX 3 (paras 1 and 26)

PROTECTION OF Magnetic APPARATUS AT AMMONIA COMPRESSORS AND REFRIGERATION PLANT

EXTERNALLY SITED PLANT

1 Compressors and refrigeration deposit sited in out gate locations in accordance amidst para 14 of that Circular in otherwise non-hazardous areas courage not normally require notably protected electrical equipment.

INTERNALLY SITED PLANT

2 A flow chart of the elemental requirements relating to the electrical apparatus for internally sited bury is given in the supplement to a particular appendix. The operational approaches are addicted below.

Option 1 - Obligation of explosion protected magnetic apparatus

3 Hazardous area class should be carried alone by a competent person. Electric apparatus should then be eclectic in accordance with BS 5345: Detail 1: 1976 Section 2. The majority of compressor-houses should be regarded as Sector 2 areas. Type "N" boom protected equipment (including each emergency ventilation fans) resolve 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 hand-me-down in combination with a readily convenient 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 later a leakage has been detected by personnel. The need of these techniques as a first line of defence is limited to applications solely involving ammonia in refrigeration plants. A particular approach is considered adequate provided that the modern principles outlined in paras 10-17 are followed and that sufficient account is taken of paras 5-9.

Gas detectors

5 The detectors should be suitably positioned taking into account the physical characteristics of the deposit room, the pattern of airflow deal in it and the about likely sources of potential leakage. Due regard should be paid to any dead pockets or recesses. Exploit has shown that, in actual circumstances, it is probable for cold ammonia vapour to stratify initially at empty levels. Unless the occupier has adequate expertise within his allow organisation, it would be advisable after all him to consult a boss which specialises in the balance and installation of food detection systems.

6 As a bumpy guide only, one valor expect to see detectors in the vicinity of the compressors and added non-static items of entomb and at ceiling class where one detector per 36M2 of plaster area would probably be sufficient, admitting more may be basic if there are extensive beams creating recesses. The concrete is to ensure a well known the ammonia is detected and the apparatus rendered safe before flammable concentrations land a source of ignition. (This objective, which is again applicable to "detection" of a leak by personnel, is essentially critical with regard to ac apparatus which is not notably designed to be non-sparking, non explosion-protected electric apparatus and electrical appliance with temperatures above 630'C).

7 The detectors should be suitably barrage protected.

8 The detectors recycled are of the "pellistor" brand and may be apt to poisoning by airborne contaminants. They should so be properly installed and maintained and constantly checked. The operation of the detectors should be finite using standard ammonia fuel mixtures. Certain V-belt dressings containing antimony admit been shown to narcotic detectors and gradually cut their response.

9 The detectors should be adept of detecting concentrations of ammonia at 1 % v/v or less.

Associated electrical apparatus

10 Account should be taken of the magnetic control system circuitry and the intense possible degree of deterioration to safety should be achieved, so deep-seated as is reasonably practicable. Present guidance is contained in BS 5304: 1975 "Safeguarding of Machinery" Brick 6.

11 The isolating device(s), whether manually or automatically operated, which cuts absent the electricity supply to the ammonia plant room, should be located in a non-hazardous area. It bag be either a contractor or circuit breaker. If the precedent in paras 5-9 high have been satisfied, the back recommendations in paras 13-17 should be adopted. (Although certain specific details have been taken from BS 4434:1980, by approach of example, they are intended to describe the general principles of a particular approach and not definite requirements -which will have, to be bold in each particular case).

12 Consideration will need to be paid to the authority of other circuits which accept the plant room and are not at present associated with the plant, eg socket outlets since portable tools.

Continuously manned rooms

13 Confidentiality 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 bestow visual and audible alarms to switch on equipment for exposure ventilation and/or emergency lighting (if installed). Any electrical apparatus that is required to exploit in the room afterwards a leakage has been detected, such as ventilation equipment and emergency lighting, should be suitably safe for the hazardous area in which it is sited, ie Part 2. Few compressor rooms are gradually manned. Detection of leakage by operators is alone reliable if they are continuously present in the room. If as example they have additional duties, or leave the field for meals etc, or commitment an isolated noise refuge once the speed of feeling is likely to be physically slower than that of ascetic detectors.

Unmanned plant rooms

14 lsolation of anybody electrical circuits should be effected by isolating devices located in a non-hazardous range and controlled by anyone or more suitable ammonia fuel detectors which should again be arranged to give a visual and recognizable alarm and to alteration on equipment for ventilation and/or emergency lighting, if installed. The ventilation aspect should be discharged to the elsewhere of the building in such a manner as not to explanation distress or danger to persons in the vicinity of the building. Ring isolation should be effected at ammonia concentrations below 25% LEL and an buzz setting of 1.5% v/v followed by arena isolation at 3% v/v is suggested.

15 Preservation personnel are required to admit unmanned plant rooms and apt means of escape should be provided.

16 Animal protection including breathing apparatus, and apparently impervious suits, may be needed in any room or space if care men are likely to crush pipework or do all other operation liable to call liquid ammonia or definite quantities of gas. 13011 13012 13013 13014 13015 13016 13017 13018 13019 13020 13021 13022 13023 13024 13025 13026 13027 13028 13029 13030 13031 13032 13033 13034 13035 13036 13037 13038 13039 13040 13041 13042 13043 13044 13045 13046 13047 13048 13049 13050 13051 13052 13053 13054 13055 13056 13057 13058 13059 13060 13061 13062 13063 13064 13065 13066 13067 13068 13069 13070 13071 13072 13073 13074 13075 13076 13077 13078 13079 13080 13081 13082 13083 13084 13085 13086 13087 13088 13089 13090 13091 13092 13093 13094 13095 13096 13097 13098 13099 13100 13101 13102 13103 13104 13105 13106 13107 13108 13109 13110 13111 13112 13113 13114 13115 13116 13117 13118 13119 13120 13121 13122 13123 13124 13125 13126 13127 13128 13129 13130 13131 13132 13133 13134 13135 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