AMMONIA COMPRESSORS AND REFRIGERATION Deposit From Jakarta Barat
INTRODUCTION
1 A certain circular gives advice on the precautions to be taken against the toxic, fire and explosion hazards presented by refrigeration systems containing ammonia. These are approximately likely to be begin by LA enforcement officers at clinical stores and food shipment warehouses. It applies to the complete system not simply the compressor house. It provides brief advice on matters of apprehension to enforcement officers pending check of BS 4434:1980.
2 Appendix 1 outlines the present principles of refrigeration, Appendix 2 gives consultation on the results of the programme of distinct visits carried out in 1983 by Branch Inspectorate (F1) to consider present standards in the cuisine industry and Appendix 3 gives authentic guidance on electrical standards. Administration officers should not overemphasise the hazards of ammonia compared along other refrigerants.
HAZARDS
Toxicity
3 Ammonia is a chemically reactive food that is very soluble in drink and is much lighter than facet (vapour density 0.59 of a well known of air). Cold vapour (e.g. from leaks) may anyway be denser than air. Despite there have been incidents of crisis to harmful concentrations of ammonia in the UK attendant have been few critical accidents. Ammonia is characterised by a simple pungent odour and is clear by most people at levels of almost 50 ppm in the atmosphere. Albeit workers become tolerant to a certain effect and in the past have been able to trade without distress at levels up to 70 ppm, presently the recommended exposure diameter for ammonia is 25 ppm, 8 date TWA (0.0025%) and the faultfinding term exposure limit is 35 ppm, 10 little TWA. At 400 ppm, around people experience immediate adenoids and throat irritation, nonetheless suffer no permanent ill-effects after 30-60 minute exposure. A grade of 700 ppm causes prompt irritation to the eyes, and a category of 1,700 ppm (0.17%) courage give rise to existing coughing and can be alarming after about 30 minutes exposure.
Exposure to concentrations superior 5,000 ppm (0.5%) since quite short periods bowl result in death. Effect to the effects of ammonia varies widely amid individuals, and the dose-response effects described raised are likely to be those adroit by the more accessible members of the population.
Fire and explosion
4 Ammonia forms a flammable batter with air at concentrations betwixt 16 and 25% v/v. Attendant have however been actually few incentive explosions involving ammonia compressor houses in the UK and everyone of the reported incidents interested ammonia leakage from plant under maintenance.
Existing guidance
5 Contemporary guidance on the precautions which should be taken along ammonia refrigeration plant may be begin in: British Standard 4434: 1980 "Requirements after all Refrigeration Safety: Part 1, General". The requirements (particularly from the f ire and bang standpoint) are similar to those in the first (1 969) version. Anyway a' full revision of BS 4434 is taking place.
Precautions
6 Beneath normal circumstances people courage not be able to bear ammonia concentrations at balanced a fraction of the flammable limit. The apt precautions are mainly those convenient against toxic effects in occupied areas and to business where sudden exposures are foreseeable, such as maintenance and fitness work, including in material filling and oil draining. Precautions across fire and explosion resolve be appropriate however, in unoccupied areas akin as compressor houses and alone plant such as impersonal stores where accumulations of vapour may go unnoticed.
PRECAUTIONS Adjacent TOXIC RISK
Respiratory protective equipment
7 Any person entering an operation in which ammonia vapour is likely to be present at a historic level (eg for recoup or fault-finding purposes) precondition wear self-contained or air passenger carrier breathing apparatus. This does not build routine visits to plant rooms etc. A ample and properly maintained couple should be conveniently sited warm to, but outside, all area in which above levels of .ammonia vapour efficacy arise. In no conclusion should anyone enter an range where a flammable combination of gas may be present. Circumstances of suitable apparatus are contained in File 2501 "Certificate of Confirmation (Breathing Apparatus)," published annually by HSE. See also Guidance Note GS 5 about entry into confined spaces.
8 Adequate respiratory protective equipment precondition be worn by every body carrying out engineering conservation work on any manufacture where there is a liability of release of ammonia. Infinite face canister respirators along type A (blue) canisters confer good protection in atmospheres up to 2% combination or 20,000 ppm, by reason of one hour. Work in akin a concentration is expected to lead to ache quickly due to fur irritation as ammonia dissolves in perspiration. A list of suitable accessory is given in arrange 2502 "Certificate of Approval (Canister Gas Respirators)". Since substantial jobs impervious suits may be essential if the gas cannot be cleared.
9 Everybody who is likely to guarantee to use respiratory protective device must be properly trained in its use and requisite be fully aware of its limitations. The accessory must be maintained, kept blank and examined at bottom once a month. Convenient records should be kept. If canister respirators are recycled there must be an alive system for deciding when the canisters should be renewed.
Evacuation and crisis procedures
10 lt is basic that a clear emergency procedure is drawn up which circumstances the precise duties of anyone staff and the arrangements by reason of evacuation, rescue, first aid, entomb isolation etc. It is frequently important that evacuation procedures are clearly set out and constantly practised where refrigeration systems are in unavailable areas. A common control which may be abundant is to use the blaze alarm provided that actuating points are forthwith available at working areas. Crew should be warned not to approach any vapour clouds. (Clouds may constantly look like steam as a result of of the cooling of the released gas).
11 Able exits should be maintained from deposit rooms at, all times. Cadre seriously affected by an ammonia dodge suffer streaming eyes and cruel coughing and rapidly come disorientated. They therefore crave clear prior knowledge of a protected exit route.
Training in deposit operation and maintenance
12 Anyone personnel involved in the deal and maintenance of the entomb must be adequately trained. The coaching should cover not alone general principles of refrigeration although also specific points alike to the particular plant. A particular applies as much to preservation contractors as to an employer's avow staff.
PLANT LOCATION
Plant not designed by reason of outdoor location
13 In the case of standard refrigeration deposit (ie plant not chiefly designed for outdoor location) emergency to excessively low aspect temperatures may cause liquefaction of ammonia within the compressor leading to compressor damage, which could be hazardous. A well known 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, point reasonably practicable, be fitted amidst explosion relief (eg by using lightweight fragile roof). Where loosely held panels are worn as explosion relief, they should be suitably mute (eg by chains) to prevent them becoming dangerous missiles in the employment of an explosion.
14 ln law to facilitate the arrangement of ventilation and bang relief, compressor-houses should associate at least one alien wall. The siting of compressors in ailing areas, basements, etc should be avoided anyplace practicable. Doors between entomb rooms or compressor-houses and further parts of the building should be self-closing and well-fitting.
Plant designed after all outdoor location
15 Only bury specifically designed for the temperature should be installed outdoors. Alike installations should be sited in a secure position in the disclose air with, if necessary, weather insurance using a Dutch barn type structure which has an evenly distributed bottom open area equivalent to at gutter 50% of the budget wall area.
Plant in workrooms
16 As a present principle the amount of entomb containing ammonia situated in workrooms and further populated areas should be minimised. Added plant such as stream drums and liquid pumps should anywhere possible be sited away from working areas. Compressors are day-to-day noisy and this is second reason for not having diehards in working areas.
Ventilation
17 Compress or houses should be provided alongside adequate and suitable ventilation to encounter the following requirements:
(1) Everyday Ventilation Sufficient permanent ventilation should be provided to avoid build up of toxic concentrations of ammonia from operational flow (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 brute ventilation.
(2) Emergency ventilation Accouterment should be made since sufficient mechanical ventilation to prevent flammable ammonia/air mixtures growing in the event of kind of foreseeable plant or operational downturn (eg valve failure). In akin circumstances the aim should be to control concentrations below 25% of the junior explosive limit (ie 4%).
18 The ventilation requirements after all a particular installation resolve depend on the type, capacity, alive conditions and location of the deposit and may require critter assessment by a ventilation creator with appropriate expertise. However, the final general points apply:
(1) permanent natural or mechanical ventilation, or a amalgam of both, may be worn for normal or crisis ventilation. Mechanical ventilation initiated by fuel detectors or manually (in the affair of continuously manned plants) may likewise be used for danger ventilation (see para 26); and Appendix 3 as electrical safety of the system;
(2) the ventilation should discharge to a safe commission in the open air;
(3) in after all the ventilation to be provided, the possible effects of cold on entomb should be taken into account (see para 12);
(4) discharge of air through cracks awake windows, doors etc, or the entry of windows or doors should not be relied on after all ventilation;
(5) the formulae in BS4434 as quantifying ventilation requirements are rules of claw based on unstated assumptions (eg they take no account of gallery size or leak rates). Inspectors should caution that the formulae may be recycled as a basic attend but discretion in their authentic application to a detailed plant should be stressed. A particular is particularly important with very large systems although the ventilation required by the formulae becomes impracticable; and
(6) it should be dominant that the standard of ventilation addicted 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. Authority of sources of ignition and entomb shutdown (see paras 22-26) should further provide protection in such circumstances. Manually operated controls since emergency ventilation should be located in a safe, definitely accessible place along along the control or switch for turning off the compressor.
Plant integrity
19 There can be serious corrosion of the flat pressure. parts of pipework and deposit due to condensation. It container progress unnoticed under lagging which is not comprehensively vapour sealed and is mostly rapid on plants which drive intermittently and pass-through OoC. The current principles relating to the protection of pressure systems are appropriate. The development should be thoroughly examined by a able person at regular intervals in accordance amidst a written scheme. There should be an operating maintenance scheme.
Pipework
20 All parts of refrigerating systems and in material pipework should be positioned or protected to minimise the hazard of impact damage, after all example by fork journey trucks. Pipework and valves should be certainly marked to indicate their contents and function.
Oil devour system
21 Many of the reported incidents involving ammonia refrigeration systems admit been the result of a malfunction of the margarine drain system (designed to visit the "carry-over" of margarine from the compressors). In around cases oil is bored from below liquid ammonia and is saturated along it. In addition the oil is viscous because it is cold. In duty to minimise the disclosure of escape from a particular cause the following measures should be advised:
(1) locus short distances are absorbed and adequate observation of the consume is possible oil consume pipes should terminate in a secure location in the expose air. Valves on any pipe extension should not admit the possibility of liquid ammonia as trapped; a bleed valve or hydrostatic alleviation valve venting to a intact place should be provided in the sections amid valves, as appropriate;
(2) a coupled valve arrangement should be provided at shortening drains. In addition to the operational booklet valve, there should be an autogenous closing spring or weight-loaded valve; and
(3) The obligation of oil drain catchpots. These are a useful feature on new plant, still existing plant cannot commonly be easily modified. Along the oil is drained, the catchpot is far-flung from the liquid ammonia/oil feedline and the catchpot is electrically annoyed to boil off any ammonia which flows as a vapour to the horizontal 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, perfectly ventilated positions and, locus reasonably practicable, in the bring to light air. Filling points should be sited abroad from sources of ignition.
PRECAUTIONS Adjacent FIRE AND EXPLOSION RISK
Sources of ignition
23 Anyone 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 as use in potentially explosive atmospheres is given in RS 5345: Article 1: 1976 "Code of Culture for the Selection, Airstrip and Maintenance of Electric Apparatus for Use in Potentially Device Atmospheres, Part 1, Elemental Requirements for all Parts of the Code"; BS 4434: 1980, Paragraph 13 "Electrical Installations". The approaches followed by the over documents differ.
25 As a modern principle, electrical equipment should be sited abroad the compressor room in a protected location. However, when it is actually sited in the room, it should be in accordance alongside the guidance given in para 27.
26 Where the ammonia compressors and refrigeration entomb are located in the same room as the foundation switch gear for the-premises removal would probably be inconvenient and costly. In akin cases, Field Consultant Class (FCG) advise on the almost suitable safety precautions in the concrete case should be sought.
Electrical apparatus selection criteria
27 The demand of electrical apparatus in refrigeration plants using ammonia has been expressed a special case as long as of the flammability characteristics of the food (high LEL and finite explosive range) and the detail that it can be detected at absolutely low levels by smell. A particular has resulted in a zip code of options which may be explicit when selecting electrical accessory for ammonia plants and these are express in Appendix 3.
OTHER RISKS
28 Refrigeration systems everyday have associated risks which may desire attention, These include the hazard of trapping in clinical stores and chills, the conduct of very cold products and microbiological problems corporate with cooling towers hand-me-down for the condenser.
ENFORCEMENT APPROACH
29 Administration officers should advise a well known ammonia refrigeration plant should accustom with the guidance in BS 4434: 1980 as amended and positive by the information in that circular. They should ever bear in mind:
(1) ammonia presents a toxic disclosure at concentrations far below those at which it presents all fire or explosion risk. Near have been 2 gassing fatalities amid 1977 and 1983 in the UK although only 3 incentive ammonia/air explosions in the bottom 20 years;
(2) the hidden consequences of an affair in terms of disability to personnel, and the current public should be assessed;
(3) BS4434 was forward published in 1969 and was not intended to be retrospective, albeit improvements in installations which pre-date the typical should be recommended, point reasonably practicable;
(4) analysis of the l983 visits energetically suggest that where dependent conditions of the plant are found there is constantly inadequate attention to withdrawal and emergency action; and
(5) where enforcement officers encounter preservation contractors they should cause enquiries about their busy practices and training.
Further advice
30 That is a complicated modern subject and there are active trade pressure groups. Administration officers are recommended to go after the advice of HSEs Operation Consultant Group (FCG) via the Governmental Enforcement Liaison Officer (ELO), along considering enforcement action.
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Ammonia is used as a refrigerant as a result of of particular thermodynamic properties which enable it to move heat far more efficiently than further refrigerant gases such as halogenated hydrocarbons. It is frequently suited to working in the operation approximately OoC to -30oC and accordingly is widely used after all food preservation, the chilling of liquids alike as milk, beer and reticent drinks, and in the actinic 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 backdrop other components such as oil separator, intercooler, liquid receiver, current drum and liquid pumps are constantly found.
3 The useful refrigeration is produced at the evaporator. Liquid ammonia at empty pressure, and hence low temperature, takes in heat by vaporising. This vapour is removed by the compressor which, in compressing it, raises the temperature from below to over ambient. The hot compressed electricity gives up the heat by condensing to a liquid in the condenser. The raised 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 remaining liquid is available after all use in the evaporator.
4 In a down-to-earth system it is likely there will be added items of plant. An margarine 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 aching high pressure liquid into the low pressure side.
Downstream of the condenser is almost a liquid receiver. Later of the reducing valve is daily found a surge cask which acts as a lake of cold liquid and evens down demand on the compressor and condenser. The liquid ammonia is drawn from the stream drum by a pump. Margarine drains may be begin on surge drums, liquid receivers, and away on large plants. Ready is also likely to be an autogenous control system on everyone but the oldest and smallest plants.
A simple practical refrigeration system
1 The design was to collect aid about a cross brick of installations. One hundred and forty eight returns were hand-me-down in the analysis which recycled the Edinburgh FCG microcomputer.
2 Returns covered a free range of processes in the bread and drinks industries. The better single sector was dairying (chilled drink supply) with substantial returns likewise from frozen food producers and impersonal stores. In the drinks region cooling and soft drinks carbonators were the main uses.
There were a accessible range of other uses reported; about parts of the cooking industry require controlled temperatures below ambient at some design of their process. A accessible 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% between 100kg and 1 tonne and 12% 1 00 kg or below.
The oldest composing 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 self-reliant compressor room. Forty-nine fee had the system charging amount 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 away of the building only. Thirty-six per cent of the further compressor rooms did not conclude self-closing doors and 17% did not believe well-fitting doors. With compressors in a independent room this is a especially large number where constant the most rudimentary precautions to bar the spread of escaping fuel has not been taken. Fifty-five per cent had condensers mounted over ground level outside - ordinarily on the roof. This raises questions of protected 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 reticent drinks plants). This points to the engagement for effective emergency procedures in the case of leakage, particularly if it is in the workroom.
5 Solo 3% of installations were identified as having pipework or plant capable of being damaged by, after all example, fork lift trucks. Moderate of the entire ballot however had unmarked pipework. (Notes of bounteous proformas suggested that a particular would receive early attention).
6 lt proved impossible to carryout meaningful analysis of the ventilation provided in compressor rooms. A average installation seemed to await largely on natural ventilation (perhaps assisted by a meager fan) for normal ventilation. Locus there was provision of ventilation exclusively for emergencies, it tended to be a autonomous system rather than a 2 momentum fan on the mundane ventilating system. Only 23% of the installations had 2 ventilation rates available and only half the ventilation systems of exclusive kind could be mathematical from outside the compressor room. Only half of these ventilation systems were necessarily controlled.
7 Only 16% of anyone system charging was done by a customer on his own; the typical arrangement was 2 men. Margarine draining was done by all man on his avow at 30% of anybody Installations. At 51 % of everyone installations it was carried down more than once a month. Only 26% of installations had spring-loaded valves or a catchpot development at oil drains. About of the rest had barely a short stub of barrel from a vessel containing liquid ammonia still by a single valve. In 71 % of cases point the oil drain was unsatisfactory inspectors express that the reasonably practicable adjustment was the fitting of self-closing valves. The 30% of installations locus one man did the butter draining on his allow included 6 which had no respirator of exclusive kind.
8 Forty-two per cent of compressor houses had no ammunition detectors. Sieger was by deep the most common supplier (60%) of anyone 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 never checked.
Approximately half of the detector installations solo had one operating level. Twenty-seven per cent of systems did not shut down the plant nonetheless merely raised the alarm. Ten per cent of the systems had no self-reliant alarm.
9 Sixty-six percent of compressor hall electrical installations were not comprehensively equipped to Zone 2 simple even where much of the deposit was under the administration of detectors. Seventy-five per cent of anybody compressor installations could be switched absent elsewhere outside the compressor foyer (even if only at the key supply). Of the remainder, the elemental switchgear was either in the compressor hall or access to it was through the compressor room.
10 Eighty-eight chunk of all sites had 2 or also sets of respiratory protection of some kind. Six installations (4%) had no one at all. At 83% of sites ready was said to be some description of training in the need of respiratory protection still only 43% had some description of systematic examination. At only 5 installations (3.4%) were ready possible limitations of operation which conflicted with plan of respiratory protection and the elemental problem seemed to be entry 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 notably because of the ammonia.
12 Twenty-seven fee of sites had Draeger (or similar) detector tubes after all measuring low concentrations of ammonia. Abounding others had sulphur sticks or hydrochloric acerbic for detecting small leaks.
13 Fifty-nine chunk of installations were maintained at first partly by contractors. Afar from a few essential suppliers and installers of device there were many civilian refrigeration engineers who solo appeared once or twice in the survey. No advice is available about the usual of training or workmanship of these contractors.
14 Fifty-five chunk of all sites appeared to believe emergency evacuation procedures (43% worn the fire alarm) however slightly fewer (50%) appeared to according any training in these procedures. Unattended 24% appeared to believe detailed rescue arrangements. Twenty-two per cent had written systems of business which appeared comprehensive and solo 34% had what appeared to be alive plant operator training.
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APPENDIX 3 (paras 1 and 26)
PROTECTION OF Electric APPARATUS AT AMMONIA COMPRESSORS AND REFRIGERATION PLANT
EXTERNALLY SITED PLANT
1 Compressors and refrigeration entomb sited in out aperture locations in accordance amidst para 14 of a well known Circular in otherwise non-hazardous areas firmness not normally require especially protected electrical equipment.
INTERNALLY SITED PLANT
2 A discharge chart of the key requirements relating to the ac apparatus for internally sited deposit is given in the supplement to that appendix. The operational approaches are disposed below.
Option 1 - Need of explosion protected magnetic apparatus
3 Hazardous area category should be carried down by a competent person. Electrical apparatus should then be select in accordance with BS 5345: Element 1: 1976 Section 2. The majority of compressor-houses should be regarded as Region 2 areas. Type "N" boom protected equipment (including each emergency ventilation fans) resolve be suitable for these locations.
Option 2 - Analysis of leaks by group or gas detectors
4 ln a particular approach, non-explosion protected electric apparatus, with qualifications, may be used in combination with a readily convenient means of isolating the ac supply. The method of achieving the final can be accomplished either no doubt after detection of a discharge by a gas detector system, or manually subsequently a leakage has been detected by personnel. The obligation of these techniques as a forward line of defence is limited to applications solely involving ammonia in refrigeration plants. A well known approach is considered competent provided that the current 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 detail the physical characteristics of the entomb room, the pattern of airflow activity in it and the about likely sources of hidden leakage. Due regard should be paid to any dead pockets or recesses. Exploit has shown that, in physical circumstances, it is supposed for cold ammonia vapour to stratify initially at flat levels. Unless the occupier has able expertise within his allow organisation, it would be advisable since him to consult a boss which specialises in the beauty and installation of food detection systems.
6 As a bumpy guide only, one might expect to see detectors in the vicinity of the compressors and added non-static items of bury and at ceiling classification where one detector per 36M2 of roof area would probably be sufficient, albeit more may be elemental if there are extensive beams creating recesses. The material is to ensure a well known the ammonia is detected and the apparatus rendered safe before flammable concentrations arrive a source of ignition. (This objective, which is further applicable to "detection" of a leak by personnel, is chiefly critical with regard to electric apparatus which is not especially designed to be non-sparking, non explosion-protected ac apparatus and electrical appliance with temperatures above 630'C).
7 The detectors should be suitably explosion protected.
8 The detectors worn are of the "pellistor" type and may be accountable to poisoning by airborne contaminants. They should therefore 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 admit been shown to narcotic detectors and gradually cut down 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 ac control system circuitry and the severe possible degree of decline to safety should be achieved, so deep-seated as is reasonably practicable. Modern guidance is contained in BS 5304: 1975 "Safeguarding of Machinery" Chunk 6.
11 The isolating device(s), whether manually or necessarily operated, which cuts absent the electricity supply to the ammonia bury room, should be located in a non-hazardous area. It container be either a architect or circuit breaker. If the precedent in paras 5-9 high have been satisfied, the final recommendations in paras 13-17 should be adopted. (Although physical specific details have been taken from BS 4434:1980, by access of example, they are intended to identify the general principles of that approach and not recognizable requirements -which will have, to be desperate in each particular case).
12 Debate will need to be paid to the agency of other circuits which admit the plant room and are not directly associated with the plant, eg socket outlets as portable tools.
Continuously manned rooms
13 Aloofness of all electrical circuits should be effected by isolating devices located in a non-hazardous area. These devices should be mathematical by push buttons forthwith outside the plant room, or objective by a gas diagnosis system as described pare 14, and arranged to bestow visual and audible alarms to switch on equipment for danger ventilation and/or emergency lighting (if installed). Any electrical apparatus that is required to engage in the room after a leakage has been detected, aforesaid as ventilation equipment and crisis lighting, should be suitably protected for the hazardous area in which it is sited, ie Region 2. Few compressor rooms are constantly manned. Detection of discharge by operators is unattended reliable if they are deliberately present in the room. If after all example they have added duties, or leave the operation for meals etc, or commitment an isolated noise refuge earlier the speed of feeling is likely to be actually slower than that of autogenous detectors.
Unmanned plant rooms
14 lsolation of anyone electrical circuits should be effected by isolating devices located in a non-hazardous operation and controlled by anybody or more suitable ammonia electricity detectors which should likewise be arranged to according a visual and distinct alarm and to about-face on equipment for ventilation and/or emergency 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. Band isolation should be effected at ammonia concentrations below 25% LEL and an bell setting of 1.5% v/v followed by arena isolation at 3% v/v is suggested.
15 Conservation personnel are required to enter unmanned plant rooms and adept means of escape should be provided.
16 Animal protection including breathing apparatus, and ostensibly impervious suits, may be needed in all room or space if care men are likely to damage pipework or do any other operation liable to call liquid ammonia or certain quantities of gas. 20010 20011 20012 20013 20014 20015 20016 20017 20018 20019 20020 20021 20022 20023 20024 20025 20026 20027 20028 20029 20030 20031 20032 20033 20034 20035 20036 20037 20038 20039 20040 20041 20042 20043 20044 20045 20046 20047 20048 20049 20050 20051 20052 20053 20054 20055 20056 20057 20058 20059 20060 20061 20062 20063 20064 20065 20066 20067 20068 20069 20070 20071 20072 20073 20074 20075 20076 20077 20078 20079 20080 20081 20082 20083 20084 20085 20086 20087 20088 20089 20090 20091 20092 20093 20094 20095 20096 20097 20098 20099 20100 20101 20102 20103 20104 20105 20106 20107 20108 20109 20110 20111 20112 20113 20114 20115 20116 20117 20118 20119 20120 20121 20122 20123 20124 20125 20126 20127 20128 20129 20130 20131 20132 20133 20134 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