Expo Technologies Principle of Operation Pressure Sensor Expo Technologies Ltd Flow Sensor Sunbury-on-Thames, England Expo Technologies, Inc Twinsburg OH, Purge Inlet USA Purge Outlet Representatives & Distributors World Wide Your Support Network Main Factory Location Minimum Pressures Purge Flow Sensor Pressurized Enclosure FE Purge Standard Minimum Pressure Outlet IEC60079-2: 2007 (Zone 1) 50 Pa / 0.5 mbar (0.2” WC) IEC60079-2: 2007 (Zone 2) 25 Pa / 0.25 mbar (0.1 WC) City Heathrow Australia AS2380 Pt 4 50 Pa / 0.5 mbar (0.2” WC) Inlet for Low Pressure Europe EN 50016 50 Pa / 0.5 mbar (0.2” WC) Protective Sensor Gas Sunbury USA NFPA 496 25 Pa/o.25 mbar (0.1” WC) Measured at the “eye” of the fan PE Gatwick Applications suitable for Exp Terminology • Static Pressurization • Control Panels – Enclosure is purged & pressurized but sealed • Switchgear • Leakage Compensation (LC) • Motors – Enclosure is purge & pressurized • Generators – Switches to small flow (tops up any leakages) • Continuous Flow (CF) • Analysers – Enclosure is purged & pressurized • Rooms/Buildings – Purge flow continues (dilutes internal release)
Basic Build Requirements Motor Purge systems • Flow meter – monitors purge (and subsequent) flow rate – no over-ride • Pressure sensor 1 – monitors minimum required overpressure Pressure sensor 2 – protection against excessive overpressure • Alarm / Isolation of electrical equipment – if overpressure falls below 0.5mb (Zone 1) System types Purge Time Equipment • IEC Standard Zone 1 Zone 2 being Division 1 Division 2 – Equal to 5x enclosure volume protected • NFPA Standard Auto-Disconnect Alarm Only – Equal to 4x enclosure volume Non-Ex Auto-Timer Manual – 10x enclosure + rotor volume (for motors) Equipment Ex px Ex pz X-Purge Z-Purge • Practical limit (user-defined?) – 60 minutes for large motors & compressors Alarm Only Ex-Equipment – 30 minutes for cabinets Manual Ex py – 10 minutes for portable equipment (Ex n / mb) Y-Purge Custom Enclosures Pneumatic Timer Based on R – C network – R = pneumatic restrictor – C = pneumatic reservoir C1 C2 C3 R
Electronic Timer Typical Settings • Accurate & Repeatable Pressure Point Pressure Leakage Nl/min – 1 to 99min (-0/+3 secs) Minimum Acceptable Pressure 150Pa, 1.5mbarg • Intrinsically Safe Normal Working Pressure 1kPa, 10mbarg Client continuous air usage – Ex ia IIC T6 • Field-replaceable battery Relief Valve Lift-off Pressure 3.0kPa, 30mbarg Clients air usage during the purge period – 3 year service life Test Pressure (RLV x 1.5) 4.5kPa, 45mbarg Must hold the pressure for 2 minutes without distortion – 10 year storage life • Global Approvals Witnessed Purge Test required for every motor to ensure – ATEX / IECEx / FM / UL (pending) compliance with the first motor tested / certified • LED Purge Progress Indicator Motor Purge Systems Typical Motor Purge System D758 Relief Valve Exe Junction Box Motor Systems G.A. Typical Internal CLAPS: Closed Loop Automatic Pressurization System
Typical Alarms Typical Installation – Drillers Console 1ZLC/bp/IS • Loss of Pressurization (Alarm/Shutdown) • Intermediate Pressure (Alarm) • Permissive Contact (Shutdown) • Electronic Options: Ex e or Ex i circuits • Pneumatic Options: Pushrod into Ex d box Expo Motor Systems Coding 1ZLC/pm/IS Non standard output options AA : Active alarm output fitted AC : Alarm cancellation circuit AS : Alarm ‘Action on pressure of flow failure’ selector valve DS : Door Switch Power interlock fitted DT : Delayed Trip after pressure or flow failure FM : Flow Meter(s) fitted MT : Mechanical Timer Hazardous Area Application Housing Standard Options OA : On/Off switch controlling protective gas or logic supply OB : On/Off switch controlling logic supply only X : covers dust and gas protection and ss : stainless steel box OC : On/Off switch controlling protective gas only has a timer pm : panel mount OV: Outlet Valve PC : PE pressure control leakage compensation valve Y : only covers dust protection AO: Alarm Only bp : back plate SS : Separate supply for protective gas and logic air Z : covers dust and gas protection but is MO: Manual Override nm : non metallic TW : Twin (or more) outputs for PEs purged in parallel . manually timed co: chassis only 5 X LC / ss / ET / OV / PA / PC / D758 System Size Purge Method ET : electronic timer. If Standard Outputs Model variant Many types available, some Each number represents a LC : (Leakage it uses a pneumatic PA : Power Alarm OEM specific, some general certain amount of air flow Compensation) timer then this block is PO : Pneumatic Output (NI/min) CF: (Continuous Flow) not included IS : Intrinsically Safe 3: 500-1500 5: 2000-6000 7: 7000- 14000 Advantages of Ex p for motors Custom Enclosures - internal • Only practical solution for high power units • Clean air purge removes environmental contaminants • Easier to achieve IIC compliance • High level of security & confidence – Monitored systems – External alarms – Power interlock
Custom enclosure - external Minimum requirements Overpressure test 1.5x manufacturers rating (typically 30–50mbar) Doors to be opened with tool (Zone 1) IP4X (Zone 1) 7Nm (4Nm on windows) UV resistance test Standard cabinets pass the above but leak! Typical enclosure systems Custom Cabinets Mini-X-Purge Interface Box Mini-Y-Purge Empty cabinet, Populated cabinet, Manufactured with Exp system Expo-inspected, ATEX or IECEx certified assembly Purge system selection Custom Enclosures Zone 1 (ATEX Cat 2) • Hazardous Area standards – Pressurized Enclosures – ATEX / IECEx / NEC / CSA / INMETRO • Expo PE2 • Zone or Division Zone 2 (ATEX Cat 3) – Increased Safety – X-purge or Z-purge – Pressurized Enclosures • Expo PE2E • Enclosure contents • Expo PE3 – Increased Safety – Ex ratings, power, T rating • Expo PE3E • Enclosure Size / Purge Time – Determines required air flow capacity
Custom Enclosures - Zone 1 (ATEX Cat 2) Expo-Intertek Schedule of Limitations 3 Heat Two temperature limiting devices must be used (one can be • Pressurized Enclosures PE2 Dissipation used to initiate a cooling system). – Expo construct OR verify clients assembly The following approved batteries are allowed: Schedule of Limitations CR2032 (VARTA or Panasonic) GA drawings & Component List Batteries or CR½ AA (VARTA or Sonnenschein) – 3 rd Party Certificate in Expo name: Cells SL-340 (Tadiran or Sonnenschein) IECEx: ITS 08.0044X ** Non-approved batteries require an Expo “Battery Test” ATEX: ITS10ATEX16944X -20 to +55°C Maximum airflow permitted: 400 litres/sec (14.125 ft 3 /sec) Ex px IIC T4 Gb Fans Inlet Position > 200 mm (7.78”) from air leakage points, e.g. Ex p IIIC T135°C door gaskets or access plate gaskets. * Can be exceeded: requires witnessed purge test Expo-Intertek Schedule of Limitations 1 Expo-Intertek Schedule of Limitations 4 Low power communication devices are allowed. Optical Devices 2100 mm (82.68”) H x 1800 mm (70.87”) W x 1000 mm Maximum (39.37”) D Devices or components mounted through the enclosure Size * Maximum volume = 3780 Litres wall must have a suitable IP rating for the enclosure and must either be metallic (or if non-metallic, must be Ex Permitted rated - demonstrates compliance with UV & Impact Purge Time must reflect 10 volume changes and be specification). Thru-Wall Purge Time between 10 and 30 minutes Components Cable Glands, Conduits and Sealing Systems shall be Ex-certified and suitable for use with the cable type and 30% minimum free space, in any cross section of any in the required Hazardous Location. Layout * plane of the enclosure. * Can be exceeded: requires witnessed purge test * Can be exceeded: requires witnessed purge test Expo-Intertek Schedule of Limitations 2 Expo-Intertek Schedule of Limitations 5 Internal closed items require minimum ventilation holes of ALL electrical supplies (power & signals) that enter the 1cm²/litre to avoid potential trapped gas. If necessary, Isolation of enclosure NOT individually protected by another explosion increase existing holes to suit or make new/additional holes Ventilation of Electrical Inputs protection technique MUST be automatically isolated (min. size 28.2mm 2 or 0.043in 2 ) Internal Items * to the Enclosure following the ALARM signal of the Expo Purge Control Closed items need ventilation distributed equally at the top system. and bottom surfaces. Internal devices with surface temperature above T4 (135 ºC) Hermetically sealed or potted devices. must be declared, and extra precautions identified and Allowed if total volume of such sealed items < 1% of the Hot Internal specified. internal free volume of the enclosure, and: Permitted Closed Components - the item does not contain any potential source of ignition, or Examples are: filament lamps, power semiconductors, Items - the item is Ex d, Ex e (no batteries), Ex i, Ex m or Ex n thyristors, heaters, power resistors, etc. certified * Can be exceeded: requires witnessed purge test
Recommend
More recommend
