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00244 

   Gas Detection 

Gas Detectors 

IMPORTANT - Gas Detectors should not be installed until all building, construction or painting work etc.. Is completed, as these 
works can effect the sensitivity and longevity of the detectors. 

Ensure that the protective cover labels (

RED

) are removed only 

after the completion of all building work and the system has 
been commissioned by the Medem engineer. 
 
The labels are required to be removed for the detectors to 
operate, but removal before the completion of works risks 
contaminating the sensor element. 

The system is capable of operating a mix of up to 16 detectors (additional power pack may be required) of different types. 
 
The detector types are: 

• 

Carbon Dioxide. 

• 

Carbon Monoxide. 

• 

Combustible gases (Methane, Propane).  

• 

Oxygen depletion and temperature.   

 
Detector location will vary dependant on the individual characteristics of the target gas that is being monitored for. See the gas 
detectors own instructions for more guidance.   

 

SEC-Lg 

Detector Information 

+VE supply & Comm’s  

From either the main panel or an 

extender. 

 

Detectors are wired in parallel and can be 

connected to one another daisy chain 

Address Selector 

Each detector must be set to its own 

address and then “learnt” using button 

(23, see page 5)

 

   Connection and addressing 

Status LED 

All current wiring regulations must be followed with reference to running low and mains voltage cables together. 

The maximum cable length between a detector and the control panel should not exceed 100 meters, if the distance between 
the main panel and the detectors is greater than 20metres a 1mm screened cable must be used on the +VE, 0v terminals 

Gas detectors, require a four core screened Belden type security cable or 600v rated BMS cable (max cable length of 
100meters.)  
Remote emergency stops and thermal links require a two core screened cable. 
Warranty will be void if Fire Protection Cable or cable over 1mm dia. is used on the SELV side. 

When addressing gas detectors CO & 

CO2 detectors must be numbered 

before natural gas detectors. 

Summary of Contents for SEC-Lg V4

Page 1: ...ety system is installed and commissioned to the satisfaction of the manufacturer A commissioning certificate must be issued to the end user along with instructions for the operation of the equipment A...

Page 2: ...ns A and B for engineer functions LED indications Power On green A blind button for displaying gas pressures on the LCD screen Gas red when active to warn of liver service Fans running light yellow B...

Page 3: ...ure check will isolate gas supply if pressure exceeds 70 mbar 17 Fill prove time for gas pressure proving see page 5 18 Timer adjustment for fan commissioning allows timed period for gas installation...

Page 4: ...as detectors 1 8 press A B together to view 9 16 Fire Test Mode Press button B three times When connected to a fire alarm panel using the fire alarm terminal no 13 the system will isolate the gas duri...

Page 5: ...1 Option Headers 18 19 21 20 Fan comm To enable the commissioning of the gas portion of the system before the ventilation interlock is completed you may temporarily disable the interlocking by pressin...

Page 6: ...e the gas detectors own instructions for more guidance SEC Lg Detector Information VE supply Comm s From either the main panel or an extender Detectors are wired in parallel and can be connected to on...

Page 7: ...een 1m and 3m from the potential source Care should be taken so they are not located close to the edge of a canopy or in direct flow of the supply or extract ventilation For additional information or...

Page 8: ...iple connect in parrallel Live feed through the Medem CM2M K2 channel current Monitor fans Fan speed controls Fan live Supply Fire Alarm Requires a volt free NC contact Where using 3 phase fans interl...

Page 9: ...s fitted the correct way round Note there is no flow through the pressure sender unit it is purely reading the pressures either side of the valve Correct Pressur e Solenoid Never mount the valve such...

Page 10: ...Solenoid coil of the valve should never be mounted below the horizontal Pressure sender unit should never be mounted upside down to protect from water ingress Approx 400mm length INLET PORT OUTLET PO...

Page 11: ...ld be wired in series with the EM stop buttons To EM Stop connections in the panel Indicator bar shows when pressed Normal EM Stop Activated Multiple Stop Buttons Single Stop Buttons Resetting indicat...

Page 12: ...er Medem UK will exchange faulty valves for return to the manufacturer 5 Where a Medem UK engineer or another company appointed by Medem UK commission and installed system then that system will carry...

Page 13: ...essed the display detectors button whilst checking on the LCD display that all the detectors have been recognised by the panel A recognised detector will appear as CO Carbon Monoxide CM combustible CH...

Page 14: ...ssure test If at any point the fans stop running opening the S1 or E1 contact the system will isolate the gas and report fans not running Check that the fans are not only switched on but actually runn...

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