Presentation to. IOSH Food and Drink Group. Danny McDougall Richard Perkin

Transcription

1 Presentation to IOSH Food and Drink Group Danny McDougall Richard Perkin 0

2 Refrigerant Gas Detection System Types Electronic EDL Infra-red CPC 1

3 Refrigerant Gas Detection Electronic - Basic Components The DETECTION UNIT Gas Sensors UPS (Battery Backup) Audible / Visual Alarm 2

4 Refrigerant Gas Detection Electronic Sensor Types GAS SENSOR TYPES Electro-chemical Cells Pellistor Sensor (Catalytic) Semi-conductor Sensors 3

5 Refrigerant Gas Detection Infra-red Basic Components DETECTION UNIT (vacuum pump and analyser) Sampling Tube and Filters UPS (Battery Backup) Audible / Visual Alarm 4

6 Refrigerant Gas Detection Unit Installation Where? The DETECTION UNIT Engineers Office Generally Outside of the Plantroom areas Control Panel Switch Room 5

7 Refrigerant Gas Detection Sensor Installation Where? GAS SENSORS (Maintenance Areas) Compressor Mechanical Shaft Seals + Other Surge Vessels With Open Drive Liquid Pumps Valve Stations In Void Areas Etc.. 6

8 Why is Ammonia Detection Required? Ammonia is a Category B2 Refrigerant TOXIC and FLAMMABLE Duty to minimise risks to staff and public under DSEAR2002 and Management of Safety and Health at Work Regulations 7

9 Flammability Flammable at concentrations between 15% and 30% Ignition temperature of 630 o C EN 378 states But for systems containing a charge > 50kg Leak detection must be fitted 8

10 Detection Levels Leak detection must activate a low level alarm at 500 ppm: Visual and audible alarms in the vicinity of the plant room Alarm repeated in a manned area Initiate plant room ventilation Must activate a high level alarm at 30,000 ppm: Alarm escalated Refrigeration system shut down Electrical supply to plant room is isolated Ventilation and leak detection continues (if ATEX rated) 9

11 Detection Levels In addition HIGH PRESSURE RECEIVER Systems containing an Ammonia charge > 3,000kg must have a remotely operated liquid line valve EXPANSION VALVE CONDENSER COMPRESSOR EVAPORATOR Leak detection must be incorporated in the heat transfer circuit of indirect systems Leak detectors must be suitable for their use and must be calibrated by a competent company (at least annually) 10

12 HFC Leak Inspection Intervals System charge between 3 and 30kg: Manual leakage inspection once a year Must keep written records of leakages and repairs System charge between 30 and 300kg: Manual leakage inspection twice a year System charge over 300kg: Manual leakage inspection quarterly Fixed leak detection system halves manual inspection intervals 11

13 DSEAR 2002 UK implementation of ATEX 94/4/EC Aimed at mitigating or reducing risks posed by flammable substances Identifying areas that may contain explosive atmosphere (Zoning) Removing / reducing sources of leakage Removing sources of ignition Requires site specific risk assessment Requires compliance to EN378 Informing staff / public of risks 12

14 Toxicity Ammonia concentration in air (ppm) Health symptoms <25 Detectable by smell. Maximum Permissible Exposure Limit 30 Uncomfortable, breathing support required. Maximum exposure 15 minutes 100 Irritated eyes, throat, mucous membranes 140 Moderate eye irritation, no long term effects if exposure < 2hours 400 Moderate throat irritation. Damage of mucous membranes with > 1 hour exposure 500 Immediately dangerous to life (IDLH) 1,000 Caustic to airway 1,700 Fatal after short exposures < 30 minutes 5,000 Immediate hazard to life >15,000 Full body protection required 13

15 Alarming for Toxicity Suggest Low-Level alarm at 25 or 35 ppm Valve stations and production areas as well as plant room Alarm repeating in manned area (gatehouse, reception) Should not be needed for low charge outdoor plant Leak detection for HCFCs, HFCs, HCs oxygen deprivation Mandatory for HFC charge over 300kg F-Gas Regulations