AMMONIA COMPRESSORS AND REFRIGERATION Entomb From Jakarta Selatan
INTRODUCTION
1 A particular circular gives advice on the precautions to be taken across the toxic, fire and barrage hazards presented by refrigeration systems containing ammonia. These are around likely to be begin by LA enforcement officers at analytic stores and food shipment warehouses. It applies to the exhaustive system not simply the compressor house. It provides temporary advice on matters of anxiety to enforcement officers pending check of BS 4434:1980.
2 Appendix 1 outlines the present principles of refrigeration, Appendix 2 gives encouragement on the results of the programme of appropriate visits carried out in 1983 by Branch Inspectorate (F1) to deal with present standards in the bread industry and Appendix 3 gives authentic guidance on electrical standards. Imposition officers should not overemphasise the hazards of ammonia compared with other refrigerants.
HAZARDS
Toxicity
3 Ammonia is a chemically reactive ammunition that is very soluble in rain and is much lighter than aspect (vapour density 0.59 of a particular of air). Cold vapour (e.g. from leaks) may ever be denser than air. Albeit there have been incidents of emergency to harmful concentrations of ammonia in the UK there have been few bad accidents. Ammonia is characterised by a usual pungent odour and is conspicuous by most people at levels of about 50 ppm in the atmosphere. Albeit workers become tolerant to that effect and in the antiquity have been able to field 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 caviling term exposure limit is 35 ppm, 10 little TWA. At 400 ppm, about people experience immediate snout and throat irritation, nonetheless suffer no permanent ill-effects after 30-60 minute exposure. A category of 700 ppm causes actual irritation to the eyes, and a category of 1,700 ppm (0.17%) firmness give rise to standing coughing and can be dangerous after about 30 minutes exposure.
Exposure to concentrations superior 5,000 ppm (0.5%) after all quite short periods bowl result in death. Impression to the effects of ammonia varies widely amid individuals, and the dose-response effects described above are likely to be those expert by the more accessible members of the population.
Fire and explosion
4 Ammonia forms a flammable blend with air at concentrations amid 16 and 25% v/v. Ready have however been literally few incentive explosions involving ammonia compressor houses in the UK and anybody of the reported incidents absorbed ammonia leakage from deposit under maintenance.
Existing guidance
5 New guidance on the precautions which should be taken alongside ammonia refrigeration plant may be create in: British Standard 4434: 1980 "Requirements by reason of Refrigeration Safety: Part 1, General". The requirements (particularly from the f ire and boom standpoint) are similar to those in the advance (1 969) version. Anyway a' full revision of BS 4434 is taking place.
Precautions
6 Under normal circumstances people resolve not be able to bear ammonia concentrations at constant 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, such as maintenance and fitness work, including in concrete filling and oil draining. Precautions adjacent fire and explosion courage be appropriate however, in unoccupied areas alike as compressor houses and solo plant such as impersonal stores where accumulations of vapour may go unnoticed.
PRECAUTIONS Con TOXIC RISK
Respiratory protective equipment
7 Any person entering an operation in which ammonia vapour is expected to be present at a extraordinary level (eg for recoup or fault-finding purposes) requisite wear self-contained or air shuttle breathing apparatus. This does not build routine visits to deposit rooms etc. A ample and properly maintained brace should be conveniently sited close to, but outside, exclusive area in which over levels of .ammonia vapour might arise. In no terms should anyone enter an range where a flammable consolidation of gas may be present. Terms of suitable apparatus are contained in Organize 2501 "Certificate of Approval (Breathing Apparatus)," published annually by HSE. See likewise Guidance Note GS 5 regarding entry into confined spaces.
8 Adequate respiratory protective equipment must be worn by every body carrying out engineering conservation work on any plan where there is a disclosure of release of ammonia. Full face canister respirators alongside type A (blue) canisters confer good protection in atmospheres up to 2% combination or 20,000 ppm, as one hour. Work in alike a concentration is acceptable to lead to ache quickly due to fur irritation as ammonia dissolves in perspiration. A list of suitable accessory is given in file 2502 "Certificate of Approval (Canister Gas Respirators)". After all substantial jobs impervious suits may be essential if the gas cannot be cleared.
9 Anybody who is likely to need to use respiratory protective device must be properly old-time in its use and precondition be fully aware of its limitations. The appliance must be maintained, kept bright and examined at first once a month. Convenient records should be kept. If canister respirators are worn there must be an operating system for deciding at the canisters should be renewed.
Evacuation and emergency procedures
10 lt is elemental that a clear exposure procedure is drawn up which circumstances the precise duties of anyone staff and the arrangements since evacuation, rescue, first aid, bury isolation etc. It is mostly important that evacuation procedures are definitely set out and always practised where refrigeration systems are in busy areas. A common control which may be enough is to use the heat alarm provided that actuating points are instantly available at working areas. Crew should be warned not to approach any vapour clouds. (Clouds may day-to-day look like steam as long as of the cooling of the released gas).
11 Adequate exits should be maintained from plant rooms at, all times. Cadre seriously affected by an ammonia dodge suffer streaming eyes and cruel coughing and rapidly grow into disorientated. They therefore require clear prior knowledge of a intact exit route.
Training in plant operation and maintenance
12 Everyone personnel involved in the force and maintenance of the entomb must be adequately trained. The drill should cover not unattended general principles of refrigeration although also specific points like to the particular plant. A well known applies as much to care contractors as to an employer's avow staff.
PLANT LOCATION
Plant not designed by reason of outdoor location
13 In the affair of standard refrigeration bury (ie plant not especially designed for outdoor location) exposure 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 therefore be sited in a compressor architecture 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 nothing fragile roof). Where loosely held panels are recycled as explosion relief, they should be suitably mute (eg by chains) to prevent them becoming dangerous missiles in the affair of an explosion.
14 ln direction to facilitate the plan of ventilation and boom relief, compressor-houses should couple at least one external wall. The siting of compressors in debilitated areas, basements, etc should be avoided anyplace practicable. Doors between deposit rooms or compressor-houses and additional parts of the architecture should be self-closing and well-fitting.
Plant designed after all outdoor location
15 Only plant specifically designed for the humidity should be installed outdoors. Akin installations should be sited in a safe position in the bare air with, if necessary, weather insurance using a Dutch parking lot type structure which has an evenly distributed first open area equivalent to at first 50% of the allocation wall area.
Plant in workrooms
16 As a ongoing principle the amount of plant containing ammonia situated in workrooms and added populated areas should be minimised. Extra plant such as flow drums and liquid pumps should everywhere possible be sited elsewhere from working areas. Compressors are everyday noisy and this is second reason for not having authority in working areas.
Ventilation
17 Compress or houses should be provided with adequate and suitable ventilation to defy the following requirements:
(1) Mundane Ventilation Sufficient permanent ventilation should be provided to bar build up of toxic concentrations of ammonia from operational discharge (eg from seals, glands etc). It is possible that the redrafted British Classic will insist on mechanical car ventilation rather than await on rather uncertain natural ventilation.
(2) Emergency ventilation Accouterment should be made by reason of sufficient mechanical ventilation to avoid flammable ammonia/air mixtures increasing in the event of moderately foreseeable plant or operational downturn (eg valve failure). In alike circumstances the aim should be to keep concentrations below 25% of the second-string explosive limit (ie 4%).
18 The ventilation requirements as a particular installation firmness depend on the type, capacity, active conditions and location of the entomb and may require animal assessment by a ventilation creator with appropriate expertise. However, the behind general points apply:
(1) enduring natural or mechanical ventilation, or a alliance of both, may be recycled for normal or exposure ventilation. Mechanical ventilation initiated by electricity detectors or manually (in the case of continuously manned plants) may further 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 by reason of the ventilation to be provided, the likely effects of cold on bury should be taken into explanation (see para 12);
(4) leakage of air through cracks alive windows, doors etc, or the opening of windows or doors should not be relied on by reason of ventilation;
(5) the formulae in BS4434 by reason of quantifying ventilation requirements are rules of claw based on unstated assumptions (eg they get no account of hall size or leak rates). Inspectors should admonish that the formulae may be used as a basic escort but discretion in their careful application to a objective plant should be stressed. A particular is particularly important amidst very large systems when the ventilation required by the formulae becomes impracticable; and
(6) it should be best that the standard of ventilation disposed by the formulae in BS 4434: 1980 is not intended to deal with prolonged releases from essential plant failure. However, the recent is very unlikely to continue in properly designed, constructed and maintained plant. Agency of sources of ignition and bury shutdown (see paras 22-26) should again provide protection in such circumstances. Manually operated controls as emergency ventilation should be located in a safe, decidedly accessible place along alongside the control or switch for turning off the compressor.
Plant integrity
19 There can be serious corrosion of the empty pressure. parts of pipework and deposit due to condensation. It bowl progress unnoticed under lagging which is not comprehensively vapour sealed and is mostly rapid on plants which run intermittently and pass-through OoC. The ongoing principles relating to the protection of pressure systems are appropriate. The development should be thoroughly examined by a adept person at regular intervals in accordance along a written scheme. Ready should be an operating maintenance scheme.
Pipework
20 All parts of refrigerating systems and in concrete pipework should be positioned or secure to minimise the hazard of impact damage, after all example by fork drive trucks. Pipework and valves should be clearly 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 show up the "carry-over" of butter from the compressors). In about cases oil is bored from below liquid ammonia and is saturated amidst it. In addition the margarine is viscous because it is cold. In duty to minimise the hazard of escape from a certain cause the following measures should be advised:
(1) location short distances are interested and adequate observation of the devour is possible oil consume pipes should terminate in a intact location in the disclose air. Valves on any pipe extension should not enter the possibility of liquid ammonia as trapped; a bleed valve or hydrostatic assistance valve venting to a secure place should be provided in the sections 'tween valves, as appropriate;
(2) a dual valve arrangement should be provided at shortening drains. In addition to the operational brochure valve, there should be an automatic closing spring or weight-loaded valve; and
(3) The need of oil drain catchpots. These are a advantageous feature on new plant, still existing plant cannot generally be easily modified. Advanced the oil is drained, the catchpot is far-flung from the liquid ammonia/oil feedline and the catchpot is electrically enraged to boil off all ammonia which flows as a vapour to the empty pressure side of the system. At the catchpot is warm, it is likewise isolated on the vapour folio and the oil is before drained from it.
Ammonia filling point
22 Ammonia filling points should be located in safe, perfectly ventilated positions and, where reasonably practicable, in the bring to light air. Filling points should be sited elsewhere from sources of ignition.
PRECAUTIONS Con FIRE AND EXPLOSION RISK
Sources of ignition
23 Everyone likely sources of ignition (naked flames etc) should be eliminated from compressor houses and from the prompt vicinity of externally located plant.
Electrical equipment
24 Encouragement on electrical apparatus by reason of use in potentially explosive atmospheres is given in RS 5345: Design 1: 1976 "Code of Culture for the Selection, Airstrip and Maintenance of Ac Apparatus for Use in Potentially Explosive Atmospheres, Part 1, Key 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 current principle, electrical equipment should be sited outside the compressor room in a safe location. However, when it is approximately sited in the room, it should be in accordance with the guidance given in para 27.
26 Point the ammonia compressors and refrigeration entomb are located in the clone room as the foundation switch gear for the-premises deportation would probably be inconvenient and costly. In akin cases, Field Consultant Division (FCG) advise on the about suitable safety precautions in the concrete case should be sought.
Electrical accessory selection criteria
27 The commitment of electrical apparatus in refrigeration plants using ammonia has been expressed a special case as of the flammability characteristics of the ammunition (high LEL and finite explosive range) and the article that it can be detected at actually low levels by smell. A well known has resulted in a home of options which may be express when selecting electrical appliance for ammonia plants and these are express in Appendix 3.
OTHER RISKS
28 Refrigeration systems constantly have associated risks which may desire attention, These include the hazard of trapping in clinical stores and chills, the charge of very cold products and microbiological problems joint with cooling towers hand-me-down for the condenser.
ENFORCEMENT APPROACH
29 Application officers should advise a particular ammonia refrigeration plant should acclimate with the guidance in BS 4434: 1980 as amended and plus by the information in that circular. They should ever bear in mind:
(1) ammonia presents a toxic liability at concentrations far below those at which it presents each fire or explosion risk. There have been 2 gassing fatalities 'tween 1977 and 1983 in the UK however only 3 incentive ammonia/air explosions in the bottom 20 years;
(2) the potential consequences of an case in terms of ailment to personnel, and the current public should be assessed;
(3) BS4434 was first published in 1969 and was not intended to be retrospective, admitting improvements in installations which pre-date the typical should be recommended, where reasonably practicable;
(4) analysis of the l983 visits energetically suggest that where dependent conditions of the bury are found there is constantly inadequate attention to evacuation and emergency action; and
(5) location enforcement officers encounter preservation contractors they should achieve enquiries about their busy practices and training.
Further advice
30 A certain is a complicated industrialized subject and there are athletic trade pressure groups. Imposition officers are recommended to go after the advice of HSEs Operation Consultant Group (FCG) via the Domestic Enforcement Liaison Officer (ELO), ahead considering enforcement action.
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Ammonia is recycled as a refrigerant as of particular thermodynamic properties which facilitate it to move melt far more efficiently than added refrigerant gases such as halogenated hydrocarbons. It is mostly suited to working in the operation approximately OoC to -30oC and accordingly is widely used since food preservation, the chilling of liquids akin as milk, beer and peaceful drinks, and in the alchemical industry. New systems endure to be installed.
2. A simple system theoretically needs 4 components:
(1) evaporator;
(2) compressor;
(3) condenser; and
(4) reducing valve
In culture other components such as shortening separator, intercooler, liquid receiver, flood drum and liquid pumps are constantly found.
3 The useful refrigeration is produced at the evaporator. Liquid ammonia at empty pressure, and hence empty temperature, takes in simmer by vaporising. This vapour is removed by the compressor which, in compressing it, raises the altitude from below to over ambient. The hot compressed food gives up the melt by condensing to a liquid in the condenser. The above pressure liquid then passes buttoned up the pressure reducing valve to the evaporator. At the valve the liquid is cooled as some vapour flashes off. The resting liquid is available since use in the evaporator.
4 In a practical system it is fair there will be increased items of plant. An shortening separator removes suspended butter carried over from the compressor and either returns it to the (pressurised) crank-case or holds it by reason of draining in some way. There may be a multi-stage compressor amidst an intercooler. This is cooled by aching high pressure liquid into the flat pressure side.
Downstream of the condenser is approximately a liquid receiver. Downstream of the reducing valve is everyday found a surge cask which acts as a pond of cold liquid and evens alone demand on the compressor and condenser. The liquid ammonia is drawn from the current drum by a pump. Margarine drains may be do on surge drums, liquid receivers, and elsewhere on large plants. Attendant is also likely to be an self control system on anybody but the oldest and smallest plants.
A simple practical refrigeration system
1 The intend was to collect advice about a cross brick of installations. One hundred and forty eight returns were recycled in the analysis which hand-me-down 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 rain supply) with substantial returns again from frozen food producers and scientific stores. In the drinks part cooling and soft drinks carbonators were the preeminent uses.
There were a open range of other uses reported; approximately parts of the bread industry require controlled temperatures below ambient at some design of their process. A free range of sizes of installations from 45 kg to 45 tonne chargeweight were reported, 13% were raised 5 tonnes, 40% between 1 and 5 tonnes, 35% between 100kg and 1 tonne and 12% 1 00 kg or below.
The oldest fundamental reported was pre-war and ready was a fairly alike spread of age from 1960 to the present.
3 Eighty-nine per cent of installations had a self-reliant compressor room. Forty-nine chunk had the system charging amount in the compressor foyer and 38% had it outdoors. Twenty-seven per cent of the pattern 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 believe self-closing doors and 17% did not conclude well-fitting doors. With compressors in a autonomous room this is a exceptionally large number where constant the most rudimentary precautions to avert 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 secure access and also dodge in the event of an emergency.
4 Thirty-six percent, had the evaporator in the workroom. (These were continually product freezers in the frozen cooking sector and carbonators at the peaceful drinks plants). This points to the commitment for effective emergency procedures in the employment of leakage, particularly if it is in the workroom.
5 Alone 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 bounteous proformas suggested that a well known would receive early attention).
6 lt proved impossible to carryout meaningful inquiry of the ventilation provided in compressor rooms. A mediocre installation seemed to rely largely on natural ventilation (perhaps assisted by a limited fan) for normal ventilation. Location there was provision of ventilation exclusively for emergencies, it tended to be a nonpartisan system rather than a 2 acceleration fan on the frequent ventilating system. Only 23% of the installations had 2 ventilation rates applicable and only half the ventilation systems of exclusive kind could be objective from outside the compressor room. Only half of these ventilation systems were naturally controlled.
7 Only 16% of everyone system charging was done by a customer on his own; the usual arrangement was 2 men. Shortening draining was done by everybody man on his grant at 30% of anybody Installations. At 51 % of everyone installations it was carried alone more than once a month. Solo 26% of installations had spring-loaded valves or a catchpot plan at oil drains. Almost of the rest had hardly a short stub of barrel from a vessel containing liquid ammonia closed by a single valve. In 71 % of cases point the oil drain was unsatisfactory inspectors explicit that the reasonably practicable adjustment was the fitting of self-closing valves. The 30% of installations point one man did the margarine draining on his allow included 6 which had no respirator of any kind.
8 Forty-two per cent of compressor houses had no ammunition detectors. Sieger was by deep the most common supplier (60%) of everyone detection systems. The around common service period of twice per year reflects a certain company's normal service contract. Nineteen per cent of detector systems were don't hold your breath 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 deposit was under the administration of detectors. Seventy-five per cent of everybody compressor installations could be switched away elsewhere outside the compressor entrance (even if only at the key supply). Of the remainder, the elemental switchgear was either in the compressor gallery or access to it was through the compressor room.
10 Eighty-eight chunk of all sites had 2 or also sets of respiratory insurance of some kind. Six installations (4%) had nobody at all. At 83% of sites ready was said to be some character of training in the commitment of respiratory protection still only 43% had some description of systematic examination. At solo 5 installations (3.4%) were attendant possible limitations of field which conflicted with plan of respiratory protection and the key problem seemed to be entry up ladders or alive congested items of plant.
11 Forty-seven per cent of sites had reviving device available usually for ongoing first aid rather than exclusively because of the ammonia.
12 Twenty-seven chunk of sites had Draeger (or similar) detector tubes since measuring low concentrations of ammonia. Alive with others had sulphur sticks or hydrochloric piquant for detecting small leaks.
13 Fifty-nine bonus of installations were maintained at bottom partly by contractors. Apart from a few fundamental suppliers and installers of apparatus there were many civil refrigeration engineers who unattended appeared once or twice in the survey. No aid is available about the usual of training or workmanship of these contractors.
14 Fifty-five chunk of all sites appeared to accept emergency evacuation procedures (43% recycled the fire alarm) still slightly fewer (50%) appeared to bestow any training in these procedures. Unattended 24% appeared to admit detailed rescue arrangements. Twenty-two per cent had written systems of trade which appeared comprehensive and only 34% had what appeared to be active 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 bury sited in out door locations in accordance along para 14 of a well known Circular in otherwise non-hazardous areas boldness not normally require exclusively protected electrical equipment.
INTERNALLY SITED PLANT
2 A leakage chart of the elemental requirements relating to the electrical apparatus for internally sited plant is given in the supplement to a certain appendix. The operational approaches are disposed below.
Option 1 - Obligation of explosion protected electrical apparatus
3 Hazardous area grade should be carried aside by a competent person. Ac apparatus should then be preferred in accordance with BS 5345: Design 1: 1976 Section 2. The mass of compressor-houses should be regarded as District 2 areas. Type "N" bang protected equipment (including any emergency ventilation fans) firmness be suitable for these locations.
Option 2 - Analysis of leaks by crew or gas detectors
4 ln a certain approach, non-explosion protected ac apparatus, with qualifications, may be recycled in combination with a readily available means of isolating the ac supply. The method of achieving the latter can be accomplished either necessarily after detection of a discharge by a gas detector system, or manually later a leakage has been detected by personnel. The commitment of these techniques as a leading line of defence is half to applications solely involving ammonia in refrigeration plants. A particular approach is considered adequate 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 history the physical characteristics of the plant room, the pattern of airflow action in it and the about likely sources of hidden leakage. Due regard should be paid to each dead pockets or recesses. Adventure has shown that, in definite circumstances, it is supposed for cold ammonia vapour to stratify initially at flat levels. Unless the occupier has apt expertise within his grant organisation, it would be advisable by reason of him to consult a company which specialises in the balance and installation of electricity detection systems.
6 As a choppy guide only, one potency 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 beam area would probably be sufficient, although 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 appliance rendered safe before flammable concentrations appear a source of ignition. (This objective, which is further applicable to "detection" of a leak by personnel, is mostly critical with regard to magnetic apparatus which is not exclusively designed to be non-sparking, non explosion-protected electric apparatus and electrical apparatus with temperatures above 630'C).
7 The detectors should be suitably bang protected.
8 The detectors worn are of the "pellistor" type and may be subject to poisoning by airborne contaminants. They should therefore be properly installed and maintained and constantly checked. The operation of the detectors should be narrow using standard ammonia fuel mixtures. Certain V-belt dressings containing antimony conclude been shown to drug detectors and gradually cut down their response.
9 The detectors should be adequate of detecting concentrations of ammonia at 1 % v/v or less.
Associated electric apparatus
10 Account should be taken of the ac control system circuitry and the acute possible degree of downturn to safety should be achieved, so deep-seated as is reasonably practicable. Ongoing 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 plant room, should be located in a non-hazardous area. It bowl be either a architect or circuit breaker. If the precedent in paras 5-9 raised have been satisfied, the backward recommendations in paras 13-17 should be adopted. (Although actual specific details have been taken from BS 4434:1980, by approach of example, they are intended to identify the general principles of that approach and not noticeable 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 admit the plant room and are not presently 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 immediately outside the plant room, or scientific by a gas discovery system as described pare 14, and arranged to according visual and audible alarms to reversal on equipment for exposure ventilation and/or emergency lighting (if installed). Exclusive electrical apparatus that is required to employ in the room after a leakage has been detected, alike as ventilation equipment and crisis lighting, should be suitably secure for the hazardous operation in which it is sited, ie Region 2. Few compressor rooms are gradually manned. Detection of leakage by operators is unattended reliable if they are continuously present in the room. If after all example they have further duties, or leave the area for meals etc, or demand an isolated noise refuge already the speed of impression is likely to be physically slower than that of self detectors.
Unmanned plant rooms
14 lsolation of everyone electrical circuits should be effected by isolating devices located in a non-hazardous area and controlled by everybody or more suitable ammonia fuel detectors which should also be arranged to bestow a visual and definite alarm and to about-face on equipment for ventilation and/or danger lighting, if installed. The ventilation condition should be discharged to the away of the building in akin a manner as not to explanation distress or danger to persons in the vicinity of the building. Round isolation should be effected at ammonia concentrations below 25% LEL and an alarm setting of 1.5% v/v followed by arena isolation at 3% v/v is suggested.
15 Maintenance personnel are required to admit unmanned plant rooms and adept 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 preservation men are likely to damage pipework or do all other operation liable to announce liquid ammonia or actual quantities of gas. 19009 19010 19011 19012 19013 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 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