Skip to content

Safety Valve AT 4537, 4538, 4537D, 4538D

Safety valve with proportional opening characteristics. Flanged connections. Nodular iron or steel. Soft- or metallic sealing disc. DN25/40-100/150, PN40

Dimension range25-100
PN40
Temperature range-85 to +450°C
MaterialNodular iron, steel

Variations

Article number Amount
AT 4537D4

Product information

Main facts

Dimension rangePNTemperature rangeMaterial

DN 25-100

40-60 - 350 ºCNodular iron
DN 25-10040-85 - 450 ºCSteel

Range of Application

Safety valve with proportional characteristics for hot water boilers and large heat-exchangers. Suitable as overflow valve at constant back-pressure and a large flow.

Quality Assurance

Approved by TÜV and several other classification authorities.
Type approved by DNV as proportional safety valve on hot water boilers.
Fulfils the requirements according to ISO 4126.
Certificate SS-EN 10204, type 2, 3 and from most of the classification authorities.
Type of certificate has to be specified upon ordering.

CE-marking
Meets the requirements in AFS 2016:1 and 2014/68/EU (Pressure Equipment Directive) according to category IV, fluids group 1 and 2.


Material Specification

AT 4537/4537D AT 4538/4538D
1Body 0.7043/1.0619/SA 216 WCB
nodular iron Gr.60-40-18
2Seat1.4404/316L1.4404/316L
3Disc1.4122/1.4122/
hardened stainless steelhardened stainless steel
4Spindle1.4021/4201.4021/420
5Spring1.1200, 1.8159, 1.1200, 1.8159,
1.7102/carbon steel1.7102/carbon steel
6Bonnet0.7040, 0.7043, 1.0619/0.7040, 0.7043, 1.0619/
nodular iron Gr.60-40-18,nodular iron Gr.60-40-18,
SA 216 WCBSA 216 WCB
7Guide1.4104, 1.0501, 0.7040/1.4104, 1.0501, 0.7040/
chrome- or carbon steelchrome- or carbon steel
8Spring plate 2 pcs1.0718/steel1.0718/steel
9Adjusting screw1.4104 PTFE/chrome steel PTFE1.4404 PTFE/316L PTFE
10Ball 1.3541/hardened stainless steel1.3541/hardened stainless steel
11aCap (2) 1.0718 or 0.7043/1.0718 or 0.7043/
12L13 or Gr.60-40-1812L13 or Gr.60-40-18
11bLever (4) 1.0718 or 0.7043/1.0718 or 0.7043/
12L13 or Gr.60-40-1812L13 or Gr.60-40-18
12Soft seal forEPDM (as standard)EPDM (as standard)
AT4537D/4538D
13Bonnet0.7040, 0.7043, 1.0619/0.7040, 0.7043, 1.0619/
nodular iron Gr.60-40-18, nodular iron Gr.60-40-18,
SA 216 WCBSA 216 WCB

Dimension and Weight

DN Inlet253240506580100
DN Outlet40506580100125150
Flow diameter Ø23293746607492
A360456497544654731788
B100110115120140160180
C105115140150170195220
D150200250300350400450
Weight11141824345879
Measurements in mm, weight in kg.

Function and Design

Spring loaded and directly acting safety valve with proportional characteristics. Disc with lifting aid gives a large discharge capacity. If possible, a soft sealing disc should be used since it has better tightness and is easier to renovate. Standard O-ring is EPDM for AT 4537D and AT 4538D for e.g. water and steam at max 150oC.

Technical Information

Overpressure
The safety valve is fully open at an overpressure exceeding the set pressure with a maximum of 10 %.
For set pressure lower than 1,0 bar, the overpressure is set pressure + 0,1 bar.
If lower overpressure is requested please contact Armatec.

Blowdown

Blowdown

Blowdown

Steam/air/gases:Max 10% at set pressure ≥3,0 bar
Max 0,3 bar at set pressure <3,0 bar
Liquids:Max 20% at set pressure ≥3,0 bar
Max 0,6 bar at set pressure <3,0 bar
If lower blowdown pressure is requested please contact Armatec.

Pressure and Temperature

AT 4537 AT 4538
Set pressure Temp.Set presureTemp.
max.-60°C tomax.-85°C to
DNbar +350°Cbar +450°C
25 40 40
32 40 40
40 40 40
50 40 40
65 40 40
80 40 40
100 40 40

Temperature max +150°C for valves with EPDM O-ring disc (AT 4537D och AT 4538D).
Pressure and temperatures according to applied standards for each valve material.
At temperatures above 200°C the temperature has to be specified in the order, so that a high temperature spring is used.
If other temperatures and pressures limits are requested please contact Armatec.

Soft sealing

Temperature range soft sealed safety valves (standard O-ring is EPDM):
O-ringNeoprene (CR) K -40°C to +100°C, e.g. refrigants
Ethylene (EPDM) D -45°C to +150°C, e.g. hot water and low temperature steam
Viton (FPM) L -20°C to +180°C, e.g. oil and air

Additional information

Sizing based on submitted data can be performed on request.
Please state: Fluid, density (for liquids), capacity/power, maximum temperature and set pressure
Bar implies bar gauge: bar(ö), bar(g), bar(e), atö or kg/cm2 if nothing else is stated.
Nm3/h implies "free" capacity air/gas (N=normal) and is equal with m3/h if other is not stated.

At temperatures above 200oC the temperature has to be specified in the order, so that a high temperature spring is used.
Min. set pressure 1 barg for soft sealed valves.
Lower set pressures on request.

Pressure and temperatures acc. to applied standards for respective valve material.

Coefficient of discharge steam/gases αd D/G
0,7

Coefficient of discharge liquids αd F
0,45

Flow diameter, Do see Dimension and weight.

Sizing DN25-50

DN 25 32 40 50
Seat23 mm 29 mm 37 mm 46 mm
Pset
barSteamAir Water SteamAirWaterSteamAirWaterSteamAirWater
0,2 152 1805789 241 2879200393 46615000608 72023111
0,5 236 2898189 374 46013000610 74821222943 115632778
1 342 43011078544 68417667887 1111286671367 171144333
2 548 69715667 870 1108248891411 1800405562189 277862667
3 737 94719222 1167 1500305561900 2444496672944 377876778
4 919 117822111 1456 1889352222378 3067573333667 474488667
5 1100 142224778 1744 2267394442844 3700641114400 571199111
6 1278 166727111 2033 2656431113311 4322702225122 6689108556
7 1456 191129333 2322 3033466673778 4944758895844 7656117778
8 1633 215631333 2600 3422497784244 5578811116567 8622125556
9 1811 238933222 2889 3811528894711 6200860007278 9589133333
10 2000 263335000 3178 4189556675178 6833906678000 10556140000
12 2356 312238444 3744 4967610006100 8078993339433 12444153333
14 2711 360041444 4322 5733658897033 933310733310867 14333165556
16 3078 408944333 4889 6500704447967 1058911444412222 16333177778
18 3433 456747000 5456 7267747788889 1177812222213667 18222187778
20 3789 505649556 6033 8044787789822 1300012777815111 20222197778
22 4156 554452000 6611 88118266710756 1433313444416556 22111207778
24 4522 602254333 7189 95788633311667 1556614000018000 24111216667
26 4878 651156556 7767 103448988912556 1677814666719444 26000225556
28 5244 698958667 8344 111119322213556 1800015222221000 27889234444
30 5611 747860667 8922 118899644414444 1933315666722444 29889243333
32 5978 795662667 9511 125569966715444 205561622222388931778251111
34 -844464667 -13333102778-21778167778-33778258889
36 -893366444 -14111105667-23111172222-35667265556
38 -941168333 -14889108556-24333176667-37667273333
40 -990070111 -15667111111-25556181111-39556280000
Pset = set pressure
According to applied standards the value above should be multiplied with the safety factor 0,9.
Saturated steam in kg/h. Air in Nm3/h (free air) at 0ºC and atmospheric pressure 1013 mbar(a). Water in kg/h at 20ºC.
Capacities are given for an overpressure of 10% of set pressure.
Contact Armatec for sizing with other fluids etc.

Sizing DN65-100

DN 65 80 100
Seat60 mm 74 mm 92 mm
Pset
barSteam AirWaterSteamAirWaterSteamAirWater
0,2 1033 1222393331567 1856598892422 287892556
0,5 1600 1967556672433 2989847783767 4622131111
1 2322 2922754443544 44441144445478 6878177778
2 3722 47331066675667 72111622228756 11111251111
3 5011 64331311117622 978919888911778 15111306667
4 6244 80781511119511 1222222888914667 19000354444
5 7489 973316888911333 1477825666717556 22778396667
6 8711 1133318444413222 1722228111120444 26667434444
7 9944 1300020000015111 1977830333323333 30556468889
8 11111 1466721333316889 2222232444426222 34444501111
9 12333 1622222666718778 2477834444429111 38333532222
10 13556 1788923888920667 2733336222232000 42222561111
12 16000 2122226111124333 3233339777837667 49889614444
14 18444 2455628222228111 3733342888943444 57667663333
16 20889 2777830111131778 4233345888949222 65444708889
18 23333 3111132000035556 4733348666755000 73222752222
20 25778 3433333777839222 5233351333360667 80889793333
22 28222 3766735333343000 5733353777866556 88667831111
24 30778 4100037000046778 6233356222272333 96444868889
26 33222 4422238444450556 6733358444478222 105556904444
28 35667 4755639888954333 7233360666784000 113333937778
30 38222 5088941333358111 7744462777889889 121111971111
32 40667 5411142666761889 8244464888995778 1288891003333
34 -57444440000-88556668889-1366671034444
36 -61556452222-93667687778---
38 -64889464444-98778706667---
40 -68222476667-103889725556---
Pset = set pressure
According to applied standards the value above should be multiplied with the safety factor 0,9.
Saturated steam in kg/h. Air in Nm3/h (free air) at 0ºC and atmospheric pressure 1013 mbar(a). Water in kg/h at 20ºC.
Capacities are given for an overpressure of 10% of set pressure.
Contact Armatec for sizing with other fluids etc.

Accessories and Options

Full lift opening characteristic, series AT 4541.
Soft sealing O-ring of Kalrez (FFKM) C for temperature range 0-250oC.
Drain plug on valve body.

Installation

ConnectionFlanges drilled acc. to
InletDIN EN 1092-1, PN40
OutletDIN EN 1092-1, PN16
See separate installation instruction. The valve should be mounted with the bonnet in vertical position.

Maintenance and Spare parts

See separate installation and maintenance instruction.

Marking

Manufacturer, Armatec article number, DN, PN, CE-marking, material and arrow showing the flow direction.
TÜV approval label with manufacturer fig. no. 441 mounted on body.
Set pressure is punched on the outlet flange and on the TÜV approval label.

How to order

Metal seated safety valve
Example: AT 4537-4-5,0-25
AT 4537-4-5,0 -25
Fig. no.DesignSet pressure (barg)DN
AT 4537=nodular iron-2=gas tight cap

AT 4538=steel-4=gas tight lifting device

How to order soft sealed

Soft seated safety valve
Example:: AT 4537D4-5,0-25
AT 4537D4-5,0 -25
Fig. no.O-ringDesignSet pressure (barg)DN
AT 4537=nodular ironD=EPDM2=gas tight cap

AT 4538=steelL=Viton®4=gas tight lifting device
K=Neoprene
N=Nitrile