STM / VGS / AVT

Data sheetTemperature controller AVT with safety temperature monitorSTM / VGS for steam (PN 25)DescriptionThe controllers are:- Type-tested acc. to EN 14597 and protectagainst exceeding temperatures:Applications:- District heating systems acc. to DIN 4747- Heating systems acc. to EN 12828 (DIN 4751)and EN 12953-6 (DIN 4752)- Water heating systems for drinking andindustrial waters acc. to DIN 4753TR(TW)700Main data: DN 15-25 kVS 1.0-6.3 m3/h PN 25 Setting ranges:- STM monitor:20 75 C / 40 95 C / 30 110 C- AVT thermostatic actuator:STW871 10 40 C / 20 70 C / 40 90 C / 60 110 Cand10 45 C / 35 70 C / 60 100 C / 85 125 CSTM/VGS and STM/AVT/VGS are self-actingproportional temperature controllers usedfor temperature control and temperaturemonitoring primarily in steam or hot waterapplications for temperatures up to 200 C. Temperature:- Steam / circulation water / glycolic waterup to 30 %: 2 200 C Connections:- Ext. thread (weld-on, thread and flangetailpieces) Flow and return mountingVGS - valve with external threadController closes on rising temperature.OrderingVGS valve 1)PictureExample 1 - STM/VGS controller:Safety temperature monitor forsteam; DN 15; kVS 1.6; PN 25; limitrange 30 110 C; Tmax 200 C;ext. thread-1 VGS DN 15 valveCode No: 065B07871 STM monitor, 30 110 CCode No: 065-0608Option:- 1 Weld-on tailpiecesCode No: 003H6908kVS(m3/h)151.6ConnectionCode No.065B07861.03.21)G¾A065B0787065B0788Cylindrical external thread acc. to ISO 228/1204.5G1A065B0789256.3G 1¼ A065B0790Temperature sensor with brass immersionpocket, length, connectionCode No.Adapter M34 M45 for connection to STM thermostat is factory assembled on the valve.(info: Adapter M34 M30 for connection to AMV(E) electrical actuators is part of the valve delivery too.)STM Safety temperature monitor (actuator)PictureAll products will be deliveredseparately. The valve VGS will bedelivered (assembled) together withan adapter M34 M45.For valvesLimit range( C)065-060830 110DN 15-5020 7540 951) Danfoss 2018.02DN(mm)210 mm, R ¾ 1)065-0609065-0610conic male thread EN 10226-1VD.JK.F5.02 1

Data sheetSTM / VGS (PN 25)Ordering (continuous)AVT thermostatic actuatorPictureExample 2 - STM/AVT/VGScontroller:Temperature controller withsafety temperature monitor forsteam; DN 15; kVS 1.6; PN 25; limitrange 30 110 C; setting range40 90 C; Tmax 200 C; ext. thread-1 VGS DN 15 valveCode No: 065B07871 STM monitor, 30 110 CCode No: 065-06081 AVT thermostatic actuator,40 90 CCode No: 065-05981 K2 combination pieceCode No: 003H6855For valvesSetting range( C)Temperature sensor with brass immersionpocket, length, connection065-0600-10 40065-060120 70210 mm, R ¾ 1)40 90DN 15-25065-060260 110065-060310 45065-060435 70065-0605255 mm, R ¾ 1) 2)60 100065-0606065-060785 1251)2)Code No.conic male thread EN 10226-1without immersion pocketAccessories for valvesPictureType designationDNConnectionCode No.003H690815Option:- 1 Weld-on tailpiecesCode No: 003H690820Weld-on tailpieces003H6909-003H69102515All products will be deliveredseparately. The valve VGS will bedelivered (assembled) together withan adapter M34 M45.External thread tailpieces2025R½Conical ext. thread acc. toEN 10226-1R¾003H6903R1003H6904003H691515Flange tailpieces20003H6902Flanges PN 25, acc. to EN 1092-2003H6916003H691725Accessories for thermostatsPictureType designationFor controllersImmersion pocket PN 252)Code No.Brass065-4416 1)STM/VGSStainless steel, mat. No. 1.4435065-4417 1)M34 1.5 mm/M45 1.5 mm003H6927Adapter 2)1)MaterialAVT/VGSCombination piece K2003H6855Combination piece K3003H6856Not for AVT thermostatic actuator code numbers: 065-0604, 065-0605, 065-0606, 065-0607Adapter for VGS combinations with thermostatic actuator AVT, temperature monitors STM and temperature limiters STLService kitsPictureType designationValve body extension with stuffing boxHousing of sensor stuffing box2 VD.JK.F5.02for valves DNkVS153.2204.5256.3Code No.003H6877for sensorsCode No.AVT R ¾065-4421 Danfoss 2018.02

Data sheetSTM / VGS (PN 25)Technical dataVGS valveNominal diameterDNkVS valuem3/hStrokemm151.01.63.220254.56.335Control ratio 1:50Control characteristiclinearCavitation factor z 0.6Leakage acc. to standard IEC 534 0.55% of kVS 0.05Nominal pressurePN25Max. differential pressurebarMedia10Steam/Circulation water/glycolic water up to 30 %Media pHMin. 7, max. 10Media temperature CvalveConnections2 200External threadtailpiecesWeld-on, external thread and flangeMaterialsValve bodyRed bronze CuSn5ZnPb (Rg5)Valve seatStainless steel, mat. No. 1.4571Valve coneStainless steel, mat. No. 1.4122Pressure relieve systemBellowsSTM Safety temperature monitor (actuator)Limit range Xs C30 110 / 20 75 / 40 95Time constant T acc. to EN 14597smax. 100Gain K smm/ KMax. adm. temperature at sensorMax. amb. temperature at thermostatNominal pressure sensorNominal pressure immersion pocketCapillary tube length0.380 C above maximum setpoint C0 70PN25m5MaterialsTemperature sensorCooperMs designImmersion pocketBrass, nickel-platedStainless steel designHandle for temp. settingmat. No. 1.4435Polyamide, glass fiber-reinforcedScale carrierPolyamideAVT Thermostatic actuatorSetting range XsTime constant T acc. to EN 14597Gain K s C 10 40 / 20 70 / 40 90 / 60 11010 45 / 35 70 / 60 100 / 85 125smax. 50 (210 mm), max. 30 (255 mm)mm/ KMax. adm. temperature at sensorMax. amb. temperature at thermostatNominal pressure sensorNominal pressure immersion pocket0.3 (210 mm); 0.7 (255 mm)50 C above maximum setpoint C0 70PN25Capillary tube length5 m (210 mm), 4 m (255 mm)MaterialsTemperature sensorImmersion pocket1)Handle for temp. settingScale carrier1) Danfoss 2018.02CooperMs designStainless steel designBrass, nickel-platedMat. No. 1.4435 (210 mm)Polyamide, glass fiber-reinforcedPolyamidefor sensor 210 mmVD.JK.F5.02 3

Data sheetSTM / VGS (PN 25)Application principlesCombinationsAVT / VGS- temperature controllerSTM / AVT / VGS- temperature controller with safetytemperature monitor4 VD.JK.F5.02STM / VGS- afety temperature monitorSTM / AVT /AVT / VGS- two temperature controllers with safetytemperature monitor Danfoss 2018.02

Data sheetSTM / VGS (PN 25)Installation positionsTemperature controller and safety temperaturemonitorUp to media temperature of 160 C temperaturecontroller AVT/VGS and safety temperaturemonitor STM/VGS can be installed in anyposition.Temperature sensorThe place of installation must be chosen in a waythat the temperature of the media is directlytaken without any delay. Avoid overheating oftemperature sensor. The temperature sensormust be immersed into the media in its full length.For higher temperatures temperature controllerAVT/VGS and safety temperature monitorSTM/VGS have to be installed horizontal andin horizontal pipes with the actuator orienteddownwards.Temperature sensors 170 mm R½ and 210 mm R¾- The temperature sensor may be installed inany position.Temperature sensor 255 mm R¾- The temperature sensor must be installed asshown on the picture.Pressure temperaturediagramCuSn5ZnPb (Rg5) PN 25Maximum allowed operating pressure as a function of media temperature (according to EN 1092-3). Danfoss 2018.02VD.JK.F5.02 5

Data sheetSTM / VGS (PN 25)Valve sizingSteam valve sizing is based on 40 % drop of thesteam pressure across the valve when fully open.At this condition the steam is travelling at orclose to its critical velocity (approx. 300 m/s) andthrottling would occur over the full valve stroke.6 VD.JK.F5.02If the steam is travelling slower than this, thenthe first part of the valve stroke would merelyincrease the velocity of the steam withoutreducing the volumetric flow. Danfoss 2018.02

Data sheetSTM / VGS (PN 25)Valve sizing (continuous)1. For saturated steam2. For superheated steamGiven data:Flow rate: 70 kg/hAbsolute inlet pressure: 5 bar (500 kPa)Given data:Flow rate: 170 kg/hAbsolute inlet pressure: 5 bar (500 kPa)Steam temperature: 190 CRemark:For this example follow dashed lineThe absolute inlet pressure is 500 kPa. Criticalpressure drop (40 % of 500 kPa) is 200 kPa. Locatethe diagonal line corresponding to the pressuredrop of 200 kPa (line A-A).Read the absolute inlet pressure on the lower lefthand scale (point B), and draw a horizontal lineacross until it meets the pressure drop diagonalA-A at point C.From this point C extend a vertical line upwardsuntil it meets the horizontal line representingthe steam flow of 70 kg/h from point D. Theintersection of this is point E.The nearest diagonal kVS line above this is lineF-F with a kVS of 1.6. If the ideal valve size is notavailable the next largest size should be selectedto ensure design flow.The pressure drop through valve at the flow rateis found by the intersection of the 70 kg/h linewith F-F (point E’) and dropping a vertical linedownwards; this actually hits the horizontal linefor 500 kPa absolute inlet pressure (point E’’)at a pressure drop diagonal of 90 kPa. This isonly 18 % of the pressure drop accross the valveand the control quality will not be good untilthe valve has partially closed. As with all steamvalves this compromise is necessary since thenext smaller valve would not pass the requiredflow (maximum flow would be about 60 kg/h;point P).The maximum flow for the same inlet pressureis found by extending the vertical line (C-E)through point E until it crosses the kVS 1.6 line F-F(point G) and reading off the flow (90 kg/h). Danfoss 2018.02Remark:For this example follow dotted lineThe procedure for superheated steam is much the same as forsaturated steam, but uses a different flow scale which slightlyelevates the readings according to the degree of superheat.As before, the diagonal critical pressure dropline A-A is located at 40 % of 500 kPa (200 kPa).The horizontal inlet pressure line throughpoint B is now extended to the left to read offthe corresponding saturated steam temperatureat point H (150 C). The difference betweenthe saturated steam temperature and thesuperheated steam temperature is190 C 150 C 40 C (see point J).The superheated steam flow 170 kg/h is foundon the upper right hand scale (point K). Fromhere the diagonal line is followed down until itmeets a vertical line from the steam temperatureelevation (40 C, point J) at point L.As before, the horizontal line through point Bis drawn to cut line A-A at point C. The pointwhere the vertical line from point C meets thehorizontal line from point L is the operatingpoint (point M). This horizontal line, L-M, is thecorrected flow line. The nearest diagonal lineabove this is line N-N with a kVS 3.2. A verticalline dropped from the intersection of L-M linewith line N-N (point M’) intersects the 500 kPaabsolute inlet pressure line (point M’’) at apressure drop diagonal of about 150 kPa.This is about 30 % of the pressure drop accrossthe valve which will give reasonable controlquality (compared to recommended ratio of40 %).VD.JK.F5.02 7

Data sheetSTM / VGS (PN 25)DesignSTM/VGS1. Valve VGS2. Valve insert3. Pressure relieved valve cone4. Valve stem5. Valve body extension6. Union nut7. Safety temperature monitorSTM8. Thermostat stem9. Setting spring fortemperature control10.Handle for limit setting,prepared for sealing11. Scale carrier12. Capillary tube13. Temperature sensor14. Immersion pocket15.Safety springAVT/VGS1. Valve VGS2. Valve insert3. Pressure relieved valve cone4. Valve stem5. Valve body extension6. Union nut7. Thermostatic actuator AVT8. Thermostat stem9. Bellows10.Setting spring for temperaturecontrol11.Handle for temperaturesetting, prepared for sealing12.Scale carrier13.Capillary tube14.Flexible protected pipe(only at AVT 255 mm)15.Temperature sensor16.Immersion pocket17. Sensor stuffing box18. Housing of sensor stuffingbox8 VD.JK.F5.02AVT 255AVT 210 Danfoss 2018.02