Elektrogas Sealing control unit LDM2 230V

LD, LDM Tightness Control Device delta-elektrogas.com EE172 -10/17  ELEKTROGAS – Technical Sheet EE172- 10/17 LD, LDM Tightness Control Device Contents Description ………………………………………..….. 2 Features ……..……………………………..……..….. 2 Functioning ………………….............……….………. 3 Applications ….……………………………..……….... 6 Sizing and adjustments ……………………………... 8 Technical specifications ………………………...…. 13 Installation …………………………………………… 15 Ordering information ……..……………...…………. 16 Accessories …………………………………………. 16 Standard and approvals ……….…………......…..... 17 Description The LD/LDM tightness control device is designed to verify the absence of inadmissible leaks in gas trains composed by automatic shutoff valves. The check can be performed before the ignition of the gas burner or after its stop. This device is used in industrial firing processes and in forced draught burners, when power is higher than 1200 kW, according to EN 746-2 and EN 676. Features Microcontroller technology Easy-to-see status of the device through high visibility LEDs Easy accessible reset button Adjustable test time to meet the plant needs Adjustable test instant Available Ex-proof version with metal enclosure for installation in Zone 2 and 22 (ATEX) Available with integrated pressure switches and/or integrated auxiliary valves Designed and manufactured according to EN 1643 WARNING This control must be installed in compliance with the rules in force. 2 / 17  ELEKTROGAS – Technical Sheet EE172- 10/17 Functioning Fig. 1 LD1 Basic version is composed by electronic control only (Fig.1). This device, coupled to an external pressure switch, checks the pressure in the test volume VT (yellow color in Fig.2), detecting potential leaks from shutoff valves. The test is performed in two steps: 1 The upstream valve is tested discharging the test volume and monitoring the pressure increasing (pressure switch on NO contact). 2 The downstream valve is tested filling the test volume and monitoring the pressure decreasing (pressure switch on NC contact). Pressure set up of the switch is usually half of inlet pressure (PT=P1/2). The operational steps of charging and discharging test volume are done by the valves V1 e V2. Fig. 2 3 / 17  ELEKTROGAS – Technical Sheet EE172- 10/17 LD3 Version with two integrated auxiliary valves for supply/discharge operations of the test volume VT (Fig.3). Fig. 3 LDM2 Version with metal enclosure and integrated pressure switch (Fig.4). Fig. 4 LDM4 Version with metal enclosure, integrated pressure switch and auxiliary valves (Fig.5). Fig. 5 4 / 17  ELEKTROGAS – Technical Sheet EE172- 10/17 Working cycle Power-up Led Fault V2 Led Fault V1 Led OK Led Test Diagnosis Led Alarm Led Power STEP DESCRIPTION tA 1 2 3 4 5 6 Power-up





NO OK Power supplied to terminal 3. Alarm Device runs a self-check (lasting tA) YES Alarm  A problem has occurred. Ready Signal F (fault) is sent to the control unit. The working cycle stops. Led2 is blinking according to the type of problem (see alarm table). Discharge Start Ready
No faults occurred. tO = 3 s Device is ready to receive the command S (start). Test V1 Discharge
 Start signal S is received. tP Device opens V2 to discharge test volume. NO PT < P1/2 Leak from V1 (time tO = 3 s). Test V1
 YES Device shuts V2 off and test for V1 begins (lasting tP). V1 OK Leak from V1

An unacceptable leak from V1 is detected. Filling Signal F (fault) is sent to the control unit. Cycle stops. to = 3 s V1 OK
 The valve V1 is tight. Test V2 Filling
 Device opens V1 to fill the test volume tP (time tO = 3 s). PT > P1/2 NO Leak from V2 Test V2
 Device shuts V2 off and test for V2 begins (lasting tP). YES Leak from V2

V2 OK An unacceptable leak from V2 is detected. Signal F (fault) is sent to the control unit. Cycle stops. V2 OK

The valve V2 is tight. OK signal is sent to the control unit.
LED switched on Tab. 1  LED blinking 5 / 17  ELEKTROGAS – Technical Sheet EE172- 10/17 Applications In addition to the basic diagram shown in Fig. 2-5, other connections are possible. System with 2 safety valves and 2 pressure switches (Fig.6). In the case of a large test volume, in order to reduce the testing time, two pressure switches can be used and set with different pressure values PL and PH. When the tightness test is finished with positive result, the OK enable signal is sent to the burner control, which can now open the V1 and V2 valves. Fig.6 System with 2 safety valves and a auxiliary valve for the discharge (Fig.7). f the second valve V2 is a slow opening type, it is necessary to install an auxiliary valve with fast opening VD for the discharge into the combustion chamber (or in the atmosphere). The device checks the tightness of the valves V1 and V2 and the auxiliary valve VD. When the tightness test is finished with positive result, the OK enable signal is sent to the burner control, which can now open the valve V2. Fig.7 6 / 17  ELEKTROGAS – Technical Sheet EE172- 10/17 Multiple burner system with 2 safety valves installed in series and auxiliary valves for the filling and discharge (Fig.8). The device checks the tightness of the main valve V1, the auxiliary valves VF and VD and the safety valves of each burner. When the tightness test is finished with a positive result, the OK enable signal opens the main valve V1 and it is sent to the burner control, to enable the opening of the valves of each burner. Fig.8 Multiple burner system with 3 safety valves installed in series (Fig.9) If the main valves V1 and V2 are slow opening is necessary to install the VF and VD auxiliary valves for filling and discharging of the test volume VT. The device checks the tightness of the main valves V1 and V2 and the auxiliary valves VF and VD. The valve V2 can only be tested if the downstream pressure is approximately equal to the atmospheric pressure and the volume of this chamber is at least equal to 5xVT. To this purpose the VK valve is opened by the Start-up signal to relieve the pressure at the value which is adjusted with the pressure switch P2 (it must be calibrated so as to detect minimum increases of pressure). When the tightness test is finished with positive result, the OK signal disables the VK valve (via the K normally closed contact), opens the valves V1 and V2 and, at the same time, enables the control units of each burner located downstream. Fig.9 7 / 17  ELEKTROGAS – Technical Sheet EE172- 10/17 Sizing and adjustments Leakage rate According the EN 1673…