Elektrogas Tightness check for gas trains. LD tightness control design

[{"filename":"LD-LDM_en.pdf","text":"LD, LDM\n\n Tightness Control Device\n\n\n\n\ndelta-elektrogas.com EE172 -02/20\n\f ELEKTROGAS – Technical Sheet EE172- 02/20\n\n\n\nLD, LDM\nTightness Control Device\n\n\nContents\n Description ………………………………………..….. 2\n Features ……..……………………………..……..….. 2\n Functioning ………………….............……….………. 3\n Applications ….……………………………..……….... 6\n Sizing and adjustments ……………………………... 8\n Technical specifications ………………………...…. 13\n Installation …………………………………………… 15\n Ordering information ……..……………...…………. 16\n Accessories …………………………………………. 16\n Standard and approvals ……….…………......…..... 17\n\n\n\n\nDescription\n The LD/LDM tightness control device is designed to verify the absence of inadmissible leaks in\n gas trains composed by automatic shutoff valves. The check can be performed before the\n ignition of the gas burner or after its stop.\n This device is used in industrial firing processes and in forced draught burners, when power is\n higher than 1200 kW, according to EN 746-2 and EN 676.\n\n\n\n\nFeatures\n Microcontroller technology\n Easy-to-see status of the device through high visibility LEDs\n Easy accessible reset button\n Adjustable test time to meet the plant needs\n Adjustable test instant\n Available Ex-proof version with metal enclosure for installation in Zone 2 and 22 (ATEX)\n Available with integrated pressure switches and/or integrated auxiliary valves\n Designed and manufactured according to EN 1643\n\n\n\n\n WARNING\n This control must be installed in compliance with the rules in force.\n\n\n\n\n 2 / 17\n\f ELEKTROGAS – Technical Sheet EE172- 02/20\n\n\nFunctioning\n\n\n\n\n Fig. 1\n\n\n\n LD1\n Basic version is composed by electronic control only (Fig.1).\n This device, coupled to an external pressure switch, checks the pressure in the test volume VT\n (yellow color in Fig.2), detecting potential leaks from shutoff valves.\n The test is performed in two steps:\n 1 The upstream valve is tested discharging the test volume and monitoring the pressure\n increasing (pressure switch on NO contact).\n 2 The downstream valve is tested filling the test volume and monitoring the pressure decreasing\n (pressure switch on NC contact).\n Pressure set up of the switch is usually half of inlet pressure (PT=P1/2).\n The operational steps of charging and discharging test volume are done by the valves V1 e V2.\n\n\n\n\n Fig. 2\n\n\n\n 3 / 17\n\f ELEKTROGAS – Technical Sheet EE172- 02/20\n\n\nLD3\nVersion with two integrated auxiliary valves for supply/discharge operations of the test volume\nVT (Fig.3).\n\n\n\n\n Fig. 3\n\n\n\nLDM2\nVersion with metal enclosure and integrated pressure switch (Fig.4).\n\n\n\n\n Fig. 4\n\n\n\nLDM4\nVersion with metal enclosure, integrated pressure switch and auxiliary valves (Fig.5).\n\n\n\n\n Fig. 5\n\n\n\n\n 4 / 17\n\f ELEKTROGAS – Technical Sheet EE172- 02/20\n\nWorking cycle\n\n\n\n Power-up Led Fault V2\n Led Fault V1\n Led OK\n Led Test\n Diagnosis Led Alarm\n Led Power\n STEP DESCRIPTION\n tA 1 2 3 4 5 6\n NO\n Power-up      \n OK Power supplied to terminal 3.\n Alarm\n Device runs a self-check (lasting tA)\n O\n YES Alarm \n A problem has occurred.\n Ready Signal F (fault) is sent to the control unit.\n The working cycle stops.\n Led2 is blinking according to the type of\n problem (see alarm table).\n Discharge Start\n Ready \n No faults occurred.\n tO = 3 s Device is ready to receive the command\n S (start).\n Test V1\n Scarico\n Discharge  \n Start signal S is received.\n tP\n Pronto Device opens V2 to discharge test\n volume.\n NO\n PT < P1/2 Leak from V1 (time tO = 3 s).\n\n\n YES\n Test V1  \n Device shuts V2 off and test for V1\n begins (lasting tP).\n V1 OK\n Leak from V1  \n An unacceptable leak from V1 is\n detected.\n Filling Signal F (fault) is sent to the control unit.\n Cycle stops.\n\n to = 3 s V1 OK  \n The valve V1 is tight.\n Test V2\n Filling  \n Device opens V1 to fill the test volume\n tP (time tO = 3 s).\n\n PT > P1/2 NO\n Leak from V2 Test V2  \n Device shuts V2 off and test for V2\n begins (lasting tP).\n YES\n\n V2 OK\n Leak from V2  \n An unacceptable leak from V2 is\n detected.\n Signal F (fault) is sent to the control unit.\n Cycle stops.\n\n V2 OK  \n The valve V2 is tight.\n OK signal is sent to the control unit.\n\n\n\n\n  LED switched on Tab. 1\n  LED blinking\n\n\n\n\n 5 / 17\n\f ELEKTROGAS – Technical Sheet EE172- 02/20\n\n\nApplications\n In addition to the basic diagram shown in Fig. 2-5, other connections are possible.\n\n\n System with 2 safety valves and 2 pressure switches (Fig.6).\n In the case of a large test volume, in order to reduce the testing time, two pressure switches can\n be used and set with different pressure values P L and PH.\n When the tightness test is finished with positive result, the OK enable signal is sent to the\n burner control, which can now open the V1 and V2 valves.\n\n\n\n\n Fig.6\n\n\n\n System with 2 safety valves and a auxiliary valve for the discharge (Fig.7).\n If the second valve V2 is a slow opening type, it is necessary to install an auxiliary valve with\n fast opening VD for the discharge into the combustion chamber (or in the atmosphere).\n The device checks the tightness of the valves V1 and V2 and the auxiliary valve V D. When the\n tightness test is finished with positive result, the OK enable signal is sent to the burner control,\n which can now open the valve V2.\n\n\n\n\n Fig.7\n\n\n\n\n 6 / 17\n\f ELEKTROGAS – Technical Sheet EE172- 02/20\n\n\n\nMultiple burner system with 2 safety valves installed in series and auxiliary valves for the\nfilling and discharge (Fig.8).\nThe device checks the tightness of the main valve V1, the auxiliary valves V F and VD and the\nsafety valves of each burner.\nWhen the tightness test is finished with a positive result, the OK enable signal opens the main\nvalve V1 and it is sent to the burner control, to enable the opening of the valves of each burner.\n\n\n\n\n Fig.8\n\n\n\n\nMultiple burner system with 3 safety valves installed in series (Fig.9)\nIf the main valves V1 and V2 are slow opening is necessary to install the VF and VD auxiliary\nvalves for filling and discharging of the test volume V T.\nThe device checks the tightness of the main valves V1 and V2 and the auxiliary valves V F and\nVD. The valve V2 can only be tested if the downstream pressure is approximately equal to the\natmospheric pressure and the volume of this chamber is at least equal to 5xVT.\nTo this purpose the VK valve is opened by the Start-up signal to relieve the pressure at the\nvalue which is adjusted with the pressure switch P 2 (it must be calibrated so as to detect\nminimum increases of pressure). When the tightness test is finished with…