Hazardous Area Equipment

explosion proof ignition control unit2 ignitor-flame

The Igniter Control System has been designed to offer maximum reliability and flexibility. It uses only one Low Tension cable to transmit the spark and also receive the 'Flame On' and 'Igniter Fault' Signal.

  • 100% Discrimination between Main and Pilot Flames
  • Low voltage from Ignition Control Unit to Igniter
  • Analogue Flame Signal Readout
  • Short Circuit Fault Detection & System Protection
  • Available for use in Zone 1 Hazardous areas. ATEX Certificate No: CESI 01 ATEX 036, Area Code II 2GD Exd IIC T6
LT300 Ignition Control System

The Igniter Control System was designed to be used in conjunction with a single electrode Gas-Air mix Igniter Rod. The Igniter Coil is mounted at the rear end of the Igniter Rod, and connections are via a 3-way plug and socket. The Igniter Coil is fed from a pulse generator, which is switched by a Thyristor. This pulsed 140VDC supply is applied to the Low Tension winding of the Coil, which in turn generates the high-tension spark.


Signals required from Control System.

  1. 24VDC Signal or a volt free closed contract for 3 seconds (Initiate Spark)
  2. Command to open Gas Valve (Timed Process)

During the Spark 'On' period the ionisation detector rejects any signals from the spark generated, this is taken cared of by the capacitor network, thus a 'Flame present' detection signal can only take place once the spark has been removed and a flame on signal from the electrode had been detected.

The flame on signal is achieved by 'Ionisation'. When a gas flame is established, this permits a positive flow of ions between the electrode and the Igniter head. This gives a variable forward resistance. The Igniter Control System has a set resistance threshold and when this threshold is reached the relay in the control system is energised indicated by LED Flame On. This change is displayed on a 0-10V analogue signal strength meter, which is incorporated into the control system to indicate when the Gas-Air mix is correct.

  • Flame off response time 1 second fixed
  • Output 1. Flame On. 1 relay changeover contacts rated 230VAC 1 Amp.
  • Output 2. 140VDC Pulse to Igniter Coil
  • Output 3. Igniter Fault Relay
  • Operating temperature 0-85 C
  • Input 1. Spark Initiation Volt Free Contact
  • Input 2. Spark Initiation 24VDC
  • Power requirements 115VAC/230VAC 50/60Hz 20VA + 10%-20%
  • Weight 10kg (Zone 1 System)
Gas-Air Pre Mix Igniter

This Igniter, of the Gas Air Mix design, produces a very hard stable gas flame and will light the main fuel under all conditions of combustion airflow.

It is possible to totally discriminate between the Igniter gas flame and main flame by incorporating our Gas Flame Ionisation detection system.

One stainless steel flexible hose is connected to the Igniter for the supply of the Gas/Air mixture from the Credfeld Gas/Air Mixer unit.

The system is connected to a local ignition plate, which provides all the necessary services. The interconnecting cable terminates in an encapsulated transormer coil on the igniter which provides the energy to produce the ignition spark and thereafter transmitting the ionisation signal to the control unit.


Exd UV10-MK2 NSC Digital Trip Amplifier Card - Applications Information - (Non self-checking variant)

uv10 mk2 uv flame viewing head Introduction

The UV10-MK2 is digital, pulse-counting, ultra-violet flame amplifier, primarily for use with the range of self-checking UV Flame Scanners, such as the UVH6, UVH8 or FP87 series. In addition, variants may be supplied for use with non self-checking scanners such as the UVH12/21, UVH32 or FP95 series. The standard unit is housed in an ABS box, 150mm x 200mm x 75mm, offering protection to IP65, but may also be fitted within alternative enclosures, including hazardous area types as shown above. The unit may be supplied fitted with an internal digital strength display, housed inside the box behind a viewing window. Alternatively, as standard portable, hand-held digital signal display may be used for initial setting up or occasional site checks.

Hand-held digital display unit hand_held digital display
Operational Description (non self-checking variant)

The signal from a standard non self-checking UV Viewing Head (when seeing flame) consists of a train of voltage pulses at a frequency of 100Hz (for 50Hz mains frequency), or 120Hz (for 60Hz mains frequency). In the UV10-MK2 NSC variant has a low signal alarm indication. When the measured pulse rate lies within a range of 10 counts above the flame count value, an additional alarm will operate, indicating a borderline signal condition.

Lamps and Controls and on the UV10-MK2 NSC
The green 'FLAME ON' LED

This will illuminate when the amplifier is receiving a flame signal having a count rate in excess of the user-set 'FLAME COUNT', and indicated that the UV10-MK2 is signalling 'Flame On. Correspondingly, the Flame relay on the UV10-MK2 NSC will energise.

The yellow 'SIGNAL' LED

This will illuminate as signal pulses are received from the viewing head. Observing the action of the LED can give an indication of the characteristics of the flame signal. For ease of viewing, individual pulses are stretched to 20ms length.

The red 'ALARM' LED

This will illumuniate, in addition to the 'Flame On' LED, if the flame signal count is within a range of 10 counts above the present flame count value, to indicate a borderline signal condition. Correspondingly, the Alarm relay on the UV10-MK2 NSC will energise. Once the flame signal exceeds this limit, only the 'Flame On' LED will be illuminated. NB The lamp will also illuminate if an urealisically low flame count value is selected.

UV10-MK2 Digital Trip Amplifer Card - Applications Information

The 'FLAME COUNT' switches

These switches allow the user to select the desired flame count value. The switch marked 'x10 COUNT' selects the 10's part of the count, and the switch marked 'x1 COUNT' the 1's part. If a count of below 5 is selected, the UV10-MK2 will go to an alarm state, since this represents an unrealistically low value of flame count.

Connector 'PL1'

This connector is used for the standard display y option described previously. The digital output is the form of a Manchester-coded pulse stream of amplitude 5V. There is also an uncommitted I/O pin for future expansion. Additionally, OV and +12V outputs are available on this connector.

Connector 'PL2'

This connector provides a pulse-width-modulated (PWM) signal output which can be utilised (in association with a 5V DC moving coil meter) to provide a quick and simple display of signal count, should a digital display unit not be available. The pulse amplitude is 5V and the pulse repetition is 40Hz. Additionally, OV and +5V outputs are available on this connector.

Additional Information:

The UV10-MK2 NSC input circuitry is electrically isolated from the rest of the electronics and in the case of 40wire UV scanners, such as the UVH12/21 and FP95, is largely unaffected by lead length between the viewing head and the amplifier. For 2-wire scanners, such as the UVH32, it is recommended that lead lengths be kept as short as possible.