Burkert Type 6440 (SKU 20092753) is a servo-assisted 2/2-way piston valve specifically optimized for use as a safety shut-off valve in fuel cell systems and other hydrogen applications. This highly compact solenoid valve delivers reliably high tightness and an extended service life. To increase pressure resistance and leak-tightness, the stopper and the core guide tube are welded together. The coils are molded with highly chemically resistant epoxy, and sliding rings are incorporated to increase the service life when operating with dry gases.

This specific model (20092753) features a G 3/8 internal thread connection, an 8.0 mm orifice, and operates within a pressure range of 0 to 25 bar. It is constructed with a durable stainless steel body and EPDM seals, making it suitable for medium temperatures ranging from -40 °C to +90 °C. The valve operates on 24 V DC and achieves an IP65 degree of protection when used with a suitable cable plug.

General Technical Data

Product Properties	Specification
Material
Seal	EPDM
Housing	Stainless steel 1.4404/316L
Coil	Epoxy
Tightness
Internal leakage rate	$1 \times 10^{-4}$ mbar l/s (>1.5 bar differential pressure)
External leakage rate	$1 \times 10^{-4}$ mbar l/s
Pressure & Flow
Pressure level	PN 40 bar (DN 6/DN 8)
Burst pressure	>250 bar for threaded body
Orifice	DN 8 (8.0 mm)
Circuit function	A (Normally closed)
Thermal insulation class	Epoxy coil class H
Performance Data
Duty cycle	100% continuous operation
Switching time (DN 6, DN 8)	Opening: 10...20 ms / Closing: 40...50 ms
Medium Data
Operating medium	Neutral gases (e.g. compressed air, nitrogen), Optimised for hydrogen
Medium temperature	-40 °C...+90 °C
Viscosity	Max. $21\text{mm}^2/\text{s}$ (21 cSt)
Environment and Installation
Installation position	As required, preferably with actuator upright
Ambient temperature	-40 °C...+55 °C / +75 °C for stationary applications depending on performance level

INFO

Measurement at +20 °C, 6 bar at the valve outlet, opening: pressure build-up 0…90 %, closing: pressure reduction 100…10 %.

Circuit Functions

Symbol	Description
	Circuit function A (CF A) 2/2-way solenoid valve Servo-controlled Normally closed

Approvals and Conformities

Explosion Protection

Optional explosion protection according to category 2 (zone 1/21) or category 3 (zone 2/22) is available for the Type 6440 series. Ex marking of the components varies based on the coil type (AC10 or AC19) and connection method (cable outlet, terminal box, or plug contacts).

North America (USA/Canada)

• UL Hazardous Locations: Optional UL Listed for Hazardous Locations for USA and Canada (Class I, Zone 1; Class I, Division 2, Group A, B, C and D; Class II + III, Division 2, Group F and G).
• CSA for Canada and the USA: The valves are CSA approved for Canada and the USA as a Safety Shutoff Valve for hydrogen according to UL 429 and CSA 139.

DNV GL Classification

Optional DNV GL classification is available for ships, offshore units, and high-speed and light craft. The products are accepted for installation on all vessels classed by DNV GL.

Material Specifications

No.	Element	Material
1	Nut	Stainless steel 1.4305/303, PTFE-coated
2	Stopper	Stainless steel 1.4113/434
3	Core guide tube	Stainless steel 1.4303/305/308
4	Guide ring	PTFE carbon-filled
5	Core	Stainless steel 1.4113/434
6	Spring	Stainless steel 1.4310/301
7	Coil	Epoxide
8	Retaining plate	Stainless steel 1.4301/304
9	Body	Stainless steel 1.4404/1.4571/316L/316Ti
10	External seal	EPDM
11	Whole piston	Stainless steel 1.4305/303, PPS, PTFE carbon-filled, EPDM

Dimensions (Threaded Variant)

Dimensions are in mm. The following dimensions apply to the threaded variant of the Type 6440 valve, which corresponds to SKU 20092753 (G 3/8 connection).

DN	A (port connection)	B	C	(D)	(E)	F	G	I	J	(P)	SW
8	G 3/8	12	50	62	74	18	M4	27	4.5	42.5	24