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Safety Shut-Off Valve RMG 790 for pre-heater hot water circuits

Operation and Maintenance, Spare Parts

Serving the Gas Industry - WORLDWIDE

790.20 edition 04/2003


790.20 p.02


1. General Remarks For technical information, different versions, and dimensions of the safety shut-off valve (SAV) RMG 790 refer to our publication ref: 790.00. Our brochure "General Operating Instructions for Gas Pressure Regulators and Safety Devices" are useful guidelines on how to fit the valve into the line, put it into service and find faults that might disturb its operation. The construction, set-up, supervision and maintenance of gas pressure regulating stations are subject to national technical rules which should be strictly observed (in Germany please refer to the DVGW Worksheets G 490, G 491 and G 495). The frequency of periodical maintenance for the safety shut-off valve RMG 790 is generally determined by the prevailing service conditions and the type and composition of the gaseous medium. We, therefore, refrain from imposing any fixed intervals and would refer you to the recommendations given by the DVGW Worksheet G 495 on "Gas Pressure Regulating Stations and Metering Stations for High Gas Volumes - Supervision and Maintenance". For maintenance, all parts are to be cleaned and subjected to a thorough visual inspection. A visual inspection should not be omitted when the course of operation or performance tests have shown lack of response accuracy. Particular care should be given to the checking of sealings and diaphragms, as well as all carrying and movable parts. Damaged parts should be replaced by new ones. The item numbers referred to in the maintenance instructions are identical to those of the spare parts drawing and spare parts lists. We recommend that a supply of components marked (*) on the spare parts drawing are held on stock by the user.

2. Special operating instructions To protect the boiler, the safety shut-off valve RMG 790 is mounted in the out-flow and return runs of the hot water circulation: Particular care should be given to the following points for the installation (the numbers in the give the positions on scheme 1): 1 The arrows on the name plate must be positionned to the heat exchanger. It is possible in any position. 2 Flanges must be to the pressure rating connection flange on the heat exchanger (it is necessary since the SAV RMG 790 is inserted between two flanges.)

3 The shut-off valves are necessary to control the function; they must be applied in the pression stage of the heating unit. It is not necessary to install these valves if isolation is possible within the heating room. (scheme 1). 4 The outlet of the control devices G 3/4 must be connected to a combined discharge and collecting line for gas and water. The collecting line must be dimensioned as follows: response pressure RMG 790 pipework < 2,5 bar R 3/4" > 2,5 bar R 1"

790.20 p.03


Scheme 1: Construction of a natural gas preheating system

heating room 10 9

gas pressure station in the open

pressure stage heating station

11 3

2

inlet side of the pressure station

12

1

8

outlet control device 7

6 heat exchanger

4

3

2

8

inlet 1

300

control device

5

5 As the discharge and collecting line is situated in the open, it must be protected against frost. If the water collecting line terminates in the building, a syphon filled with water has to be provided. In the event of damage, provision should be made to prevent gas entering via the water drain into the setting room. 6 By controlling the function of the SAV RMG 790, the pressure must be increased within the heat exchanger. The additional shut-off connection must be provided only on one device. The connecting thread is G 1/4 in the device. Note: unit supplied with a plug fitted in this connection. 7 The control manometer I shows the position of the given pressure when controlling. The measuring range should be chosen in order that the pressure can be increased by 5 to 10 bar over the response pressure of the RMG 790. In case of damage the pressure increases up to the gas inlet pressure within the heat exchanger a shut-off valve must be set between the manometer and the water circuit, the valve remains closed in a normal operating situation.

790.20 p.04


8 The control manometers II are necessary to control the function. The measuring range should be adjusted to the most permissible working pressure pzul within the heating device. The connection thread is G 1/4 in the device. Note: unit supplied with a plug fitted in this connection. A pressure switch can possibly be installed on a SAV (see remark 3, on page 5). 9 Response pressure of the safety valve, see the pressure graduating scheme. 10 The dimension regulation of the expansion vessel (see remark 5, on page 6). 11 Manometer with limiting marks for a max. working pressure in the water circuit (see remark 4, on page 5). 12 To be able to control small damages a sensing or a pressure switch can additionally be provided. A sensing switch must be installed at the highest position in the heat exchanger.

A pressure graduating scheme (example) for a preheating system which is equipped with safety shut-off valves RMG 790:

pressure value

description

p zul = 3 bar

most reliable working pressure in the heating station

psSBV= 2,5 bar

response value of shut-off valve in the heating station

p1= 2,3 bar

highest working pressure in water circuit without using the SAV RMG 790

ps SAV = 2,3 bar

response value of the SAV RMG (main valve closed)

1

safety shut-off valve RMG 790 pipe size DN 80 vertical mounting position (main valve at the top) pK = 1,6 bar

control device RMG 790 starts opening with a maximum pressure

2

pM = 1,5 bar

additional pressure switch setting

3

p2 = 1,3 bar

highest working pressure in water circuit by using the SAV RMG 790 heating station by using the SAV RMG 790

4

working range of the expansion vessel

pF = 0,5 bar

fill pressure of the expansion vessel

5

790.20 p.05


Notes: 1) The highest working pressure p1 within the water circuit and without using the safety shut-off valve RMG 790 is necessary to determine the size of the expansion vessel. This pressure is 0,1 to 0,2 bar under the response pressure pS SBV on the heating station. (Example above: p1 = pS SBV - 0,2 bar = 2,3 bar). 2) The limiting pressure pK on which the control device of the RMG 790 must be set up depends on the response pressure required pS SBV des RMG 790, on the pipe sizes of the main valve and also on the mounting position of the actuator assembly. Reference values for the limiting pressure pK can be taken from the following table:

Limiting pressure pK to be set in bar mounting position of the RMG 790 pipe size

vertical (main valve - top)

vertical (main valve - bottom )

DN 25 DN 50 DN 80 DN 100 DN 150

pS - 0,3 pS - 0,6 pS - 0,7 pS - 0,7 pS - 0,7

pS - 0,4 pS - 0,8 pS - 1,0 pS - 1,0 pS - 1,0

horizontal pS - 0,35 pS - 0,70 pS - 0,85 pS - 0,85 pS - 0,85

Example: For RMG 790, pipe sizes DN 80 in vertical mounting position (main valve at the top): pK = pS SBV - 0,7 bar = 2,3 bar - 0,7 bar = 1,6 bar

3) Addtionally to control such small damages a sensing or a pressure switch can be provided. A sensing switch must be installed at the highest position in the heat exchanger. We recommend that you install a switch with two switch positions. The first switch position can be used to start an alarm and the second one to close the SAV over an additional magnetic valve which is parallel to the control device. (see the following scheme).

2/2 waymagnetic valve

2/2 way magnetic valve for hot water PN 16, DN 13, G 3/8 i protected against explosion, Ex-s G4, currentless open with a connection cable (casted with plastic material) electr. connection

RMG-order-nr.

24 VDC

00 024 149

220 V, 50 Hz

00 024 150

A pressure switch must be installed so that the switch pressure is at least 0,2 bar over the max. working pressure within the water circuit and 0,1 to 0,2 bar under the limiting pressure on which the control device of the RMG 790 is set. 4) We recommend that you apply a second mark on the manometer of the heating station close to the stipulated limiting marks for the response pressure of the safety valve pS SBV .This mark indicates the highest working pressure p2 within the water circuit of the heating station.

790.20 p.06


5) The use of the safety shut-off valve RMG 790 gets the highest working pressure to decreasing within the water circuit of the heating station. This decrease must be taken into account by chosing a larger expansion vessel. The necessary volume of the expansion vessel can be determined according to the following formula:

p2 • ( p1 - pF ) V2 = V1 • p 1 • ( p2 - pF )

Note! use pressures as absolute values

Designation V1 = necessary volume of the expansion vessel = highest working pressure = necessary volume of the expansion vessel = highest working pressure = Filling of the expansion vessel

p1 V2 p2 pF

without SAV RMG 790

with SAV RMG 790

Example page 4: the necessary volume extensions calculated as follows: V2 = V1 •

2,3 • (3,3 - 1,5) 3,3 • (2,3 - 1,5)

= 1,6 • V1

A drain locking device between the main valve and the control device makes it possible to unscrew the control device without any water loss when controlling and maintaining. ATTENTION: • After the control device has been removed the safety shut-off valve does not function any more! • to enable a safe opening of the water locking device when installing a control device, use only the original connecting parts between the control device and the water locking device.

Special operating instructions For separate mounting elements it is recommended to pay particular attention to the following points: • sealing rings (14, 24, 32, 34, 35, 36, 38) checking of any damages, and mounting with silicone grease (50) - take the protection disc (1) out - remove the split pin (13) and the inferior disc (12) from the axis of the valve piston (16), then take the complete installation with the valve spring (5) out. Notice: when mounting do not forget the valve spring (9) • sealing rings (3, 6, 10, 18, 24, 40) according to required exchange grease with silicone grease (50). • piston (26) within the control device control the corrosion, the piston should be easy to move.

790.20 p.07


4.

Spare parts

4.1 Spare parts drawing RMG 790

36* 37 38* 39 40* 50*

*) parts to be held in stock for maintenance

790.20 p.08


4.2 Spare parts lists RMG 790 item no. description 1 2 3* 4 5 6* 7 8 9 10* 11 12 13* 14* 15 16 17 18* 19 20

protection disc cylinder dowel pin sealing ring closing screw valve o-ring cylinder dowel pin body, alternatives: PN 10/16 PN 25 PN 40 ANSI 300 ANSI 600 pressure spring sealing ring closing screw disc split pin o-ring connection bolt guide piston ENSAT- spring piece sealing ring body for water locking device sealing cone

21 22 23 24* 25 26 27 28 29 30 31 32* 33 34* 35*

threaded orifice transition piece body for control device o-ring threaded orifice valve sealing pressure spring alternatives: F 1 (Wh 2bar to 2,5 bar)

RMG stock no. material

F 2 (Wh 2,5 bar to 3,5 bar) F 3 (Wh 3,5 bar to10 bar) adjusting screw closing screw pressure spring pressure pin sealing ring straight screwing sealing ring sealing disc

DN 25

DN 50

DN 80

DN 100

DN 150

Ms NSt LM Ms Ms KV NSt

10 008 958 00 017 215 00 018 689 10 014 009 10 001 056 00 020 658 00 017 215

10 008 902 00 017 214 00 018 689 10 014 009 10 001 156 00 020 372 00 017 214

10 008 914 00 017 214 00 018 689 10 014 009 10 001 256 00 020 372 00 017 214

10 008 926 00 017 214 00 018 689 10 014 009 10 001 356 00 020 704 00 017 214

18 352 415 00 017 214 00 018 689 10 014 009 10 008 279 00 020 823 00 017 214

Ms Ms Ms Ms Ms NSt LM Ms NSt NSt KV Ms NSt St LM Ms Ms Ms NSt Ms KV Ms Ms

10 008 947 10 008 947 10 008 947 10 008 947 10 008 947 18 353 488 00 018 689 10 014 009 00 014 145 00 015 031 00 020 616 10 008 955 10 008 954 00 027 132 00 018 689 10 008 251 10 008 254 10 008 253 10 008 900 00 026 868 00 026 869 10 008 294 10 008 295

10 008 906 10 008 906 10 008 906 10 008 906 10 008 906 18 353 366 00 018 689 10 014 009 00 014 142 00 015 030 00 020 590 10 008 889 10 008 888 00 027 132 00 018 689 10 008 251 10 008 254 10 008 253 10 008 900 00 026 868 00 026 869 10 008 294 10 008 295

10 008 918 10 008 918 10 008 918 10 008 919 10 008 919 18 353 317 00 018 689 10 014 009 00 014 142 00 015 030 00 020 591 10 008 890 10 008 888 00 027 132 00 018 688 10 008 256 10 008 254 10 008 253 10 008 900 00 026 868 00 026 869 10 008 294 10 008 295

10 008 930 10 008 931 10 008 931 10 008 933 10 008 934 18 353 461 00 018 689 10 014 009 00 014 142 00 015 030 00 020 589 10 008 891 10 008 935 00 027 132 00 018 688 10 008 256 10 008 254 10 008 253 10 008 900 00 026 868 00 026 869 10 008 294 10 008 295

10 008 270 10 008 271 10 008 271 10 008 273 10 008 274 18 353 463 00 018 689 10 014 009 00 014 142 00 015 030 00 020 824 10 008 281 10 008 280 00 027 132 00 018 688 10 008 256 10 008 254 10 008 253 10 008 900 00 026 868 00 026 869 10 008 294 10 008 295

NSt NSt NSt K Ms NSt MS LM NSt KV KV

10 008 290 10 008 291 10 008 285 00 026 870 00 026 760 10 016 923 10 008 252 00 018 688 00 030 082 00 020 903 10 008 297

10 008 290 10 008 291 10 008 285 00 026 870 00 026 760 10 016 923 10 008 252 00 018 688 00 030 082 00 020 903 10 008 297

10 008 290 10 008 291 10 008 285 00 026 870 00 026 760 10 016 923 10 008 252 00 018 688 00 030 082 00 020 903 10 008 297

10 008 290 10 008 291 10 008 285 00 026 870 00 026 760 10 016 923 10 008 252 00 018 688 00 030 082 00 020 903 10 008 297

10 008 290 10 008 291 10 008 285 00 026 870 00 026 760 10 016 923 10 008 252 00 018 688 00 030 082 00 020 903 10 008 297

K

... plastic

*) Parts marked by an asterisk to be kept in stock for maintenance material key: NSt KV

... stainless steel ... rubber-like plastic material

LM Ms

...light metal ... brass

790.20 p.09


Spare parts lists RMG 790 item no. 36* 37 38* 39 40* 50*

RMG stock no. description o-ring pressure spring conduction sealing ring hydraulic part sealing ring silicon grease alternatives: - socket - tube

material

DN 25

KV Ms Cu Ms LM

00 020 805 10 008 296 00 018 810 10 008 953 00 003 916 00 027 081

DN 50

DN 80

00 020 805 10 008 296 00 018 810 10 008 903 00 003 916 00 027 081

00 020 805 10 008 296 00 018 810 10 008 915 00 003 916 00 027 081 00027079 00027081

*) Parts marked by an asterisk to be kept in stock for maintenance material key: KV Cu

... rubber-like plastic material ... copper

790.20 p.10

LM Ms

...light metal ... brass

DN 100

DN 150

00 020 805 10 008 296 00 018 810 10 008 927 00 003 916 00 027 081

00 020 805 10 008 296 00 018 810 18 352 416 00 003 916 00 027 081


790.20 p.11


We supply you with products for gas pressure regulation: RMG REGEL + MESSTECHNIK GMBH Osterholzstrasse 45, D-34123 Kassel, Germany Telephone (++49) 561 5007-0 • Fax (++49) 561 5007-107 gas pressure regulators and safety devices

RMG-GASELAN Regel + Meßtechnik GmbH Julius-Pintsch-Ring 3, D-15517 Fürstenwalde, Germany Telephone (++49) 3361 356-60 • Fax (++49) 3361 356-836 gas pressure regulating equipment, displacement meters, complete stations

Bryan Donkin RMG Gas Controls Ltd. Enterprise Drive, Holmewood, Chesterfield S42 5UZ, England Telephone (++44) 1246 501-501 • Fax (++44) 1246 501-500 gas pressure regulating equipment, below ground gas control modules

Bryan Donkin RMG Co. of Canada Ltd. 50 Clarke Street South, Woodstock, Ontario N4S 7Y5, Canada Telephone (++1) 519 5398531 • Fax (++1) 519 5373339 domestic regulators and safety devices

The other RMG Companies: RMG Messtechnik GmbH Otto-Hahn-Strasse 5, D-35510 Butzbach, Germany Telephone (++49) 6033 897-0 • Fax (++49) 6033 897-130 turbine meters, vortex meters, correctors, flow computers, odorizers

Karl Wieser GmbH Anzinger Strasse 14, D-85560 Ebersberg, Germany Telephone (++49) 8092 2097-0 • Fax (++49) 8092 2097-10

Betriebsstelle Beindersheim Heinrich-Lanz-Strasse 9, D-67259 Beindersheim/Pfalz, Germany Telephone (++49) 6233 3762-0 • Fax (++49) 6233 3762-40 data logging, monitor systems, danger alarm systems

WÄGA Wärme-Gastechnik GmbH Osterholzstrasse 45, D-34123 Kassel, Germany Telephone (++49) 561 5007-0 • Fax (++49) 561 5007-207 design and assembly of gas pressure regulating and metering stations

The RMG Group of Companies on the internet: http://www.rmg.de

Serving the Gas Industry - WORLDWIDE

We reserve the right for technical changes

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