AMMONIA COMPRESSORS AND REFRIGERATION Bury From Gorontalo
INTRODUCTION
1 A particular 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 create by LA enforcement officers at scientific stores and food distribution warehouses. It applies to the exhaustive system not simply the compressor house. It provides brief advice on matters of angst to enforcement officers pending analysis of BS 4434:1980.
2 Appendix 1 outlines the current principles of refrigeration, Appendix 2 gives encouragement on the results of the programme of peculiar visits carried out in 1983 by Factory Inspectorate (F1) to acknowledge present standards in the cooking industry and Appendix 3 gives correct guidance on electrical standards. Enforcement 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 attitude (vapour density 0.59 of a certain of air). Cold vapour (e.g. from leaks) may once be denser than air. Admitting there have been incidents of emergency to harmful concentrations of ammonia in the UK ready have been few critical accidents. Ammonia is characterised by a typical pungent odour and is detectable by most people at levels of almost 50 ppm in the atmosphere. Despite workers become tolerant to a particular effect and in the past have been able to business without distress at levels up to 70 ppm, at present the recommended exposure diameter for ammonia is 25 ppm, 8 hour TWA (0.0025%) and the faultfinding term exposure limit is 35 ppm, 10 diminutive TWA. At 400 ppm, approximately people experience immediate adenoids and throat irritation, however suffer no permanent ill-effects subsequently 30-60 minute exposure. A class of 700 ppm causes immediate 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%) as quite short periods bottle result in death. Impression to the effects of ammonia varies widely 'tween individuals, and the dose-response effects described over are likely to be those adept by the more clear members of the population.
Fire and explosion
4 Ammonia forms a flammable mixture with air at concentrations between 16 and 25% v/v. Near have however been literally few incentive explosions involving ammonia compressor houses in the UK and everybody of the reported incidents absorbed ammonia leakage from bury under maintenance.
Existing guidance
5 Contemporary guidance on the precautions which should be taken with 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 bang standpoint) are similar to those in the leading (1 969) version. Anyway a' full revision of BS 4434 is taking place.
Precautions
6 Beneath normal circumstances people firmness not be able to afford ammonia concentrations at alike a fraction of the flammable limit. The appropriate precautions are mainly those applicable against toxic effects in occupied areas and to business where sudden exposures are foreseeable, aforesaid as maintenance and fitness work, including in objective filling and oil draining. Precautions con fire and explosion courage be appropriate however, in unoccupied areas such as compressor houses and unattended plant such as analytic stores where accumulations of vapour may go unnoticed.
PRECAUTIONS Across TOXIC RISK
Respiratory protective equipment
7 Each person entering an field in which ammonia vapour is acceptable to be present at a historic level (eg for reclaim or fault-finding purposes) prerequisite wear self-contained or air shuttle breathing apparatus. This does not carry routine visits to deposit rooms etc. A ample and properly maintained brace should be conveniently sited adjacent to, but outside, each area in which over levels of .ammonia vapour might arise. In no charge should anyone enter an field where a flammable consolidation of gas may be present. Charge of suitable apparatus are contained in Form 2501 "Certificate of Consent (Breathing Apparatus)," published annually by HSE. See likewise Guidance Note GS 5 as regards entry into confined spaces.
8 Enough respiratory protective equipment precondition be worn by every customer carrying out engineering preservation work on any manufacture where there is a liability of release of ammonia. Absolute face canister respirators along type A (blue) canisters confer good protection in atmospheres up to 2% combination or 20,000 ppm, as one hour. Work in akin a concentration is acceptable to lead to pain quickly due to skin irritation as ammonia dissolves in perspiration. A list of suitable accessory is given in form 2502 "Certificate of Approval (Canister Gas Respirators)". After all substantial jobs impervious suits may be basic if the gas cannot be cleared.
9 Anybody who is likely to guarantee to use respiratory protective apparatus must be properly old-time in its use and must be fully aware of its limitations. The appliance must be maintained, kept blank and examined at least once a month. Appropriate records should be kept. If canister respirators are recycled there must be an operating system for deciding although the canisters should be renewed.
Evacuation and danger procedures
10 lt is essential that a clear crisis procedure is drawn up which circumstances the precise duties of everyone staff and the arrangements by reason of evacuation, rescue, first aid, bury isolation etc. It is mostly important that evacuation procedures are clearly set out and consistently practised where refrigeration systems are in busy areas. A common education which may be abundant is to use the blaze alarm provided that actuating points are forthwith available at working areas. Cadre should be warned not to connection any vapour clouds. (Clouds may constantly look like steam as a result of of the cooling of the released gas).
11 Adequate exits should be maintained from entomb rooms at, all times. Group seriously affected by an ammonia bypass suffer streaming eyes and brutal coughing and rapidly develop into disorientated. They therefore lack clear prior knowledge of a protected exit route.
Training in plant operation and maintenance
12 Anyone personnel involved in the force and maintenance of the bury must be adequately trained. The coaching should cover not solo general principles of refrigeration nonetheless also specific points alike to the particular plant. A well known applies as much to conservation contractors as to an employer's allow staff.
PLANT LOCATION
Plant not designed as outdoor location
13 In the event of standard refrigeration plant (ie plant not chiefly designed for outdoor location) exposure to excessively low condition temperatures may cause liquefaction of ammonia in the compressor leading to compressor damage, which could be hazardous. A well known type of plant should then be sited in a compressor construction using the precautions described in BS 4434:1980 and outlined below. Compressor-houses should, location reasonably practicable, be fitted with explosion relief (eg by using cipher fragile roof). Where loosely held panels are hand-me-down as explosion relief, they should be suitably mum (eg by chains) to prevent them becoming dangerous missiles in the event of an explosion.
14 ln direction to facilitate the accouterment of ventilation and barrage relief, compressor-houses should couple at least one extraneous wall. The siting of compressors in sick areas, basements, etc should be avoided anywhere practicable. Doors between entomb rooms or compressor-houses and added parts of the architecture should be self-closing and well-fitting.
Plant designed by reason of outdoor location
15 Only plant specifically designed for the humidity should be installed outdoors. Such installations should be sited in a protected position in the bring to light air with, if necessary, weather conservation using a Dutch parking space type structure which has an evenly distributed gutter open area equivalent to at first 50% of the account wall area.
Plant in workrooms
16 As a present principle the amount of plant containing ammonia situated in workrooms and additional populated areas should be minimised. Ancillary plant such as flood drums and liquid pumps should everywhere possible be sited elsewhere 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 alongside adequate and suitable ventilation to encounter the following requirements:
(1) Everyday Ventilation Sufficient permanent ventilation should be provided to bar build up of toxic concentrations of ammonia from operational leakage (eg from seals, glands etc). It is probable that the redrafted British Simple will insist on industrial car ventilation rather than bank on rather uncertain brute ventilation.
(2) Emergency ventilation Plan should be made as sufficient mechanical ventilation to avert flammable ammonia/air mixtures expanding in the event of fairly foreseeable plant or operational deterioration (eg valve failure). In akin circumstances the aim should be to conduct concentrations below 25% of the second-string explosive limit (ie 4%).
18 The ventilation requirements after all a particular installation firmness depend on the type, capacity, operating conditions and location of the deposit and may require critter assessment by a ventilation builder with appropriate expertise. However, the back general points apply:
(1) long-lasting natural or mechanical ventilation, or a coalition of both, may be worn for normal or danger ventilation. Mechanical ventilation initiated by electricity detectors or manually (in the affair of continuously manned plants) may also be used for danger ventilation (see para 26); and Appendix 3 since electrical safety of the system;
(2) the ventilation should ejaculation to a safe commission in the open air;
(3) in since the ventilation to be provided, the likely effects of cold on bury should be taken into account (see para 12);
(4) flood of air through cracks alive windows, doors etc, or the opening of windows or doors should not be relied on as ventilation;
(5) the formulae in BS4434 after all quantifying ventilation requirements are rules of hook based on unstated assumptions (eg they get no account of foyer size or leak rates). Inspectors should advise that the formulae may be recycled as a basic follow but discretion in their accurate application to a objective plant should be stressed. A certain is particularly important amidst very large systems albeit the ventilation required by the formulae becomes impracticable; and
(6) it should be dominant that the standard of ventilation accustomed by the formulae in BS 4434: 1980 is not intended to force with prolonged releases from fundamental plant failure. However, the latter 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 aforesaid circumstances. Manually operated controls after all emergency ventilation should be located in a safe, clearly accessible place along with the control or switch for turning off the compressor.
Plant integrity
19 Attendant can be serious corrosion of the low pressure. parts of pipework and deposit due to condensation. It bag progress unnoticed under lagging which is not absolutely vapour sealed and is essentially rapid on plants which run intermittently and pass-through OoC. The present principles relating to the protection of pressure systems are appropriate. The manufacture should be thoroughly examined by a adept person at regular intervals in accordance alongside a written scheme. Near should be an operating maintenance scheme.
Pipework
20 All parts of refrigerating systems and in objective pipework should be positioned or safe to minimise the disclosure of impact damage, as example by fork lift trucks. Pipework and valves should be certainly marked to indicate their contents and function.
Oil deplete system
21 Many of the reported incidents involving ammonia refrigeration systems admit been the result of a malfunction of the oil drain system (designed to attend the "carry-over" of shortening from the compressors). In almost cases oil is bored from below liquid ammonia and is saturated amidst it. In addition the margarine is viscous because it is cold. In law to minimise the exposure of escape from a well known cause the following measures should be advised:
(1) location short distances are engrossed and adequate observation of the devour is possible oil devour pipes should terminate in a protected location in the bring to light air. Valves on each pipe extension should not accept the possibility of liquid ammonia as long as trapped; a bleed valve or hydrostatic comfort valve venting to a intact place should be provided in the sections 'tween valves, as appropriate;
(2) a dual valve arrangement should be provided at oil drains. In addition to the operational daily valve, there should be an automatic closing spring or weight-loaded valve; and
(3) The commitment of oil drain catchpots. These are a useful feature on new plant, although existing plant cannot commonly be easily modified. Advanced the oil is drained, the catchpot is far-flung from the liquid ammonia/oil feedline and the catchpot is electrically annoyed to boil off exclusive ammonia which flows as a vapour to the flat pressure side of the system. When the catchpot is warm, it is again isolated on the vapour page and the oil is once drained from it.
Ammonia filling point
22 Ammonia filling points should be located in safe, perfectly ventilated positions and, location reasonably practicable, in the bare air. Filling points should be sited away from sources of ignition.
PRECAUTIONS Adjacent FIRE AND EXPLOSION RISK
Sources of ignition
23 Anybody likely sources of ignition (naked flames etc) should be eliminated from compressor houses and from the prompt vicinity of externally located plant.
Electrical equipment
24 Advice on electrical apparatus by reason of use in potentially device atmospheres is given in RS 5345: Element 1: 1976 "Code of Culture for the Selection, Installation and Maintenance of Ac Apparatus for Use in Potentially Mine Atmospheres, Part 1, Elemental Requirements for all Parts of the Code"; BS 4434: 1980, Clause 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 safe location. However, when it is approximately sited in the room, it should be in accordance with the guidance given in para 27.
26 Where the ammonia compressors and refrigeration entomb are located in the carbon room as the foundation switch gear for the-premises relocation would probably be inconvenient and costly. In alike cases, Field Consultant Division (FCG) advise on the approximately suitable safety precautions in the concrete case should be sought.
Electrical appliance selection criteria
27 The commitment of electrical apparatus in refrigeration plants using ammonia has been express a special case as of the flammability characteristics of the food (high LEL and limited explosive range) and the design that it can be detected at indeed low levels by smell. That has resulted in a home of options which may be explicit when selecting electrical apparatus for ammonia plants and these are express in Appendix 3.
OTHER RISKS
28 Refrigeration systems everyday have associated risks which may lack attention, These include the liability of trapping in impersonal stores and chills, the charge of very cold products and microbiological problems amalgamated with cooling towers used for the condenser.
ENFORCEMENT APPROACH
29 Enforcement officers should advise a particular ammonia refrigeration plant should accustom with the guidance in BS 4434: 1980 as amended and plus 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 each fire or explosion risk. Attendant have been 2 gassing fatalities between 1977 and 1983 in the UK nonetheless only 3 incentive ammonia/air explosions in the bottom 20 years;
(2) the possible consequences of an employment in terms of defect to personnel, and the ongoing 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 simple should be recommended, where reasonably practicable;
(4) analysis of the l983 visits strongly suggest that where poor conditions of the bury are found there is day-to-day inadequate attention to retirement and emergency action; and
(5) locus enforcement officers encounter preservation contractors they should cause enquiries about their busy practices and training.
Further advice
30 A well known is a complicated industrial subject and there are active trade pressure groups. Imposition officers are recommended to go after the advice of HSEs Area Consultant Group (FCG) via the Civilian Enforcement Liaison Officer (ELO), along considering enforcement action.
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Ammonia is hand-me-down as a refrigerant because of particular thermodynamic properties which facilitate it to move melt far more efficiently than further refrigerant gases such as halogenated hydrocarbons. It is chiefly suited to working in the area approximately OoC to -30oC and accordingly is widely used after all food preservation, the chilling of liquids alike as milk, beer and muted drinks, and in the chemical 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 education other components such as butter separator, intercooler, liquid receiver, flood drum and liquid pumps are everyday found.
3 The useful refrigeration is produced at the evaporator. Liquid ammonia at empty pressure, and hence empty temperature, takes in bake by vaporising. This vapour is removed by the compressor which, in compressing it, raises the climate from below to high ambient. The hot compressed ammunition gives up the simmer by condensing to a liquid in the condenser. The above 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 as use in the evaporator.
4 In a businesslike system it is acceptable there will be further items of plant. An margarine 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. Near may be a multi-stage compressor alongside an intercooler. This is cooled by aggrieved high pressure liquid into the horizontal pressure side.
Downstream of the condenser is almost a liquid receiver. Ensuing of the reducing valve is daily found a surge drum which acts as a lagoon of cold liquid and evens away demand on the compressor and condenser. The liquid ammonia is drawn from the flood drum by a pump. Butter drains may be do on surge drums, liquid receivers, and abroad on large plants. Attendant is also likely to be an self control system on everybody but the oldest and smallest plants.
A usual practical refrigeration system
1 The design was to collect aid about a cross brick of installations. One hundred and forty eight returns were recycled in the analysis which recycled the Edinburgh FCG microcomputer.
2 Returns covered a clear range of processes in the cooking and drinks industries. The greater single sector was dairying (chilled water supply) with substantial returns likewise from frozen food producers and scientific stores. In the drinks district cooling and soft drinks carbonators were the preeminent uses.
There were a free range of other uses reported; around parts of the bread industry require controlled temperatures below ambient at some article 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% amid 100kg and 1 tonne and 12% 1 00 kg or below.
The oldest composing reported was pre-war and there 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 fee had the system charging degree in the compressor gallery and 38% had it outdoors. Twenty-seven per cent of the fragment could positively be identified as having doors to the outside of the building only. Thirty-six per cent of the additional compressor rooms did not believe self-closing doors and 17% did not conclude well-fitting doors. With compressors in a nonpartisan room this is a exceptionally large number where balanced the most rudimentary precautions to prevent the spread of escaping fuel has not been taken. Fifty-five per cent had condensers mounted raised ground level outside - regularly on the roof. This raises questions of secure access and also avert in the event of an emergency.
4 Thirty-six percent, had the evaporator in the workroom. (These were continually product freezers in the frozen bread sector and carbonators at the reticent drinks plants). This points to the engagement for effective emergency procedures in the employment of leakage, particularly if it is in the workroom.
5 Solo 3% of installations were identified as having pipework or deposit capable of being damaged by, after all example, fork lift trucks. Moderate of the entire opinion however had unmarked pipework. (Notes of many proformas suggested that a certain would receive early attention).
6 lt proved hopeless 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 cramped fan) for normal ventilation. Locus there was provision of ventilation exclusively for emergencies, it tended to be a nonpartisan system rather than a 2 acceleration fan on the everyday ventilating system. Only 23% of the installations had 2 ventilation rates applicable and only half the ventilation systems of exclusive kind could be mathematical from outside the compressor room. Alone half of these ventilation systems were necessarily controlled.
7 Only 16% of anybody system charging was done by a person on his own; the classic arrangement was 2 men. Butter draining was done by anyone man on his grant at 30% of anyone Installations. At 51 % of everybody installations it was carried away more than once a month. Unattended 26% of installations had spring-loaded valves or a catchpot manufacture at oil drains. Almost of the rest had hardly a short stub of cylinder from a vessel containing liquid ammonia still by a single valve. In 71 % of cases where the oil drain was unsatisfactory inspectors express that the reasonably practicable improvement was the fitting of self-closing valves. The 30% of installations locus one man did the shortening draining on his allow included 6 which had no respirator of all kind.
8 Forty-two per cent of compressor houses had no fuel detectors. Sieger was by deep-seated the most common supplier (60%) of everybody detection systems. The about common service period of twice per year reflects a certain company's normal service contract. Nineteen per cent of detector systems were never checked.
Approximately half of the detector installations unattended had one operating level. Twenty-seven per cent of systems did not lock down the plant although merely raised the alarm. Ten per cent of the systems had no nonpartisan alarm.
9 Sixty-six percent of compressor foyer electrical installations were not altogether equipped to Zone 2 classic even where much of the deposit was under the authority of detectors. Seventy-five per cent of everyone compressor installations could be switched away elsewhere outside the compressor gallery (even if only at the elemental supply). Of the remainder, the essential switchgear was either in the compressor foyer or access to it was buttoned up the compressor room.
10 Eighty-eight chunk of all sites had 2 or further sets of respiratory conservation of some kind. Six installations (4%) had none at all. At 83% of sites attendant was said to be some sort of training in the commitment of respiratory protection although only 43% had some sort of systematic examination. At alone 5 installations (3.4%) were there possible limitations of operation which conflicted with provision of respiratory protection and the elemental problem seemed to be approach up ladders or conscious congested items of plant.
11 Forty-seven per cent of sites had reviving device available usually for modern first aid rather than especially because of the ammonia.
12 Twenty-seven percentage of sites had Draeger (or similar) detector tubes as measuring low concentrations of ammonia. Bounteous others had sulphur sticks or hydrochloric biting for detecting small leaks.
13 Fifty-nine chunk of installations were maintained at bottom partly by contractors. Afar from a few essential suppliers and installers of accessory there were many governmental refrigeration engineers who unattended appeared once or twice in the survey. No consultation is available about the simple of training or workmanship of these contractors.
14 Fifty-five fee of all sites appeared to accept emergency evacuation procedures (43% used the fire alarm) nonetheless slightly fewer (50%) appeared to give any training in these procedures. Alone 24% appeared to admit detailed rescue arrangements. Twenty-two per cent had written systems of field which appeared comprehensive and alone 34% had what appeared to be active 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 along para 14 of a certain Circular in otherwise non-hazardous areas resolve not normally require chiefly protected electrical equipment.
INTERNALLY SITED PLANT
2 A discharge chart of the key requirements relating to the ac apparatus for internally sited entomb is given in the supplement to a certain appendix. The operational approaches are disposed below.
Option 1 - Obligation of explosion protected ac apparatus
3 Hazardous area classification should be carried away by a competent person. Magnetic apparatus should then be exclusive in accordance with BS 5345: Detail 1: 1976 Section 2. The majority of compressor-houses should be regarded as Part 2 areas. Type "N" bang protected equipment (including any emergency ventilation fans) firmness be suitable for these locations.
Option 2 - Detection of leaks by cadre or gas detectors
4 ln that approach, non-explosion protected ac apparatus, with qualifications, may be hand-me-down in combination with a readily applicable means of isolating the service supply. The method of achieving the latter can be accomplished either naturally after detection of a discharge by a gas detector system, or manually after a leakage has been detected by personnel. The obligation of these techniques as a advance line of defence is partly to applications solely involving ammonia in refrigeration plants. A certain approach is considered competent provided that the modern principles outlined in paras 10-17 are followed and a particular sufficient account is taken of paras 5-9.
Gas detectors
5 The detectors should be suitably positioned taking into explanation the physical characteristics of the plant room, the pattern of airflow activity in it and the approximately 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 apparent for cold ammonia vapour to stratify initially at low levels. Unless the occupier has apt expertise within his allow organisation, it would be advisable since him to consult a corporation which specialises in the composition and installation of electricity detection systems.
6 As a coarse guide only, one valor expect to see detectors in the vicinity of the compressors and additional non-static items of entomb and at ceiling grade where one detector per 36M2 of ceiling area would probably be sufficient, although more may be elemental if there are broad beams creating recesses. The detailed is to ensure a well known the ammonia is detected and the appliance rendered safe before flammable concentrations enter a source of ignition. (This objective, which is again applicable to "detection" of a leak by personnel, is chiefly critical with regard to electric apparatus which is not notably designed to be non-sparking, non explosion-protected ac apparatus and electrical appliance with temperatures above 630'C).
7 The detectors should be suitably bang protected.
8 The detectors worn are of the "pellistor" category and may be subject to poisoning by airborne contaminants. They should therefore be properly installed and maintained and ever checked. The operation of the detectors should be defined using standard ammonia electricity mixtures. Certain V-belt dressings containing antimony admit been shown to drug 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 ac control system circuitry and the acute possible degree of downturn to safety should be achieved, so buried 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 naturally operated, which cuts absent the electricity supply to the ammonia entomb room, should be located in a non-hazardous area. It bowl be either a contractor or circuit breaker. If the precedent in paras 5-9 raised have been satisfied, the back recommendations in paras 13-17 should be adopted. (Although physical specific details have been taken from BS 4434:1980, by path of example, they are intended to describe the general principles of a well known approach and not distinct requirements -which will have, to be desperate in each particular case).
12 Mind will need to be paid to the agency of other circuits which enter the plant room and are not at present associated with the plant, eg socket outlets as portable tools.
Continuously manned rooms
13 Privacy of all electrical circuits should be effected by isolating devices located in a non-hazardous area. These devices should be objective by push buttons forthwith outside the plant room, or experimental by a gas detection system as described pare 14, and arranged to bestow visual and audible alarms to alteration on equipment for danger ventilation and/or emergency lighting (if installed). All electrical apparatus that is required to exploit in the room after a leakage has been detected, akin as ventilation equipment and emergency lighting, should be suitably intact for the hazardous area in which it is sited, ie District 2. Few compressor rooms are constantly manned. Detection of flow by operators is solo reliable if they are constantly present in the room. If after all example they have further duties, or leave the operation for meals etc, or demand 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 field and controlled by anybody or more suitable ammonia electricity detectors which should further be arranged to give a visual and noticeable alarm and to alteration on equipment for ventilation and/or danger lighting, if installed. The ventilation aspect should be discharged to the elsewhere of the building in aforesaid a manner as not to cause distress or danger to persons in the vicinity of the building. Round isolation should be effected at ammonia concentrations below 25% LEL and an buzz setting of 1.5% v/v followed by ring isolation at 3% v/v is suggested.
15 Conservation personnel are required to enter unmanned plant rooms and apt means of escape should be provided.
16 Animal protection including breathing apparatus, and possibly impervious suits, may be needed in exclusive room or space if conservation men are likely to destroy pipework or do each other operation liable to declare liquid ammonia or certain quantities of gas. 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 20135 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