BURKERT 345758 (Type 2100) is a pneumatically operated 2/2-way angle seat valve engineered for decentralized process automation in hygienic, utility, and demanding industrial installations. The valve features a DN15 orifice, NPT 1/2 internal threaded port connections, and an integrated 50 mm (Size D) pneumatic piston actuator. Built with a cast CF3M stainless steel body, an internal self-adjusting PTFE V-ring packing gland, and a PTFE seat seal, the assembly provides tight shut-off according to DIN EN 12266-1 Leakage Rate A across operating pressures up to 25 bar(g) and fluid temperatures from -10 °C to +185 °C.

Operating Principle and Control Function

BURKERT 345758 operates under Control Function A (CFA), functioning as a normally closed (NC) 2/2-way valve. In the rest position without pilot air pressure, internal pre-tensioned stainless steel springs push the piston and valve spindle downward, pressing the PTFE swivel plate firmly against the valve seat.

This specific model is configured for flow direction below the seat (closing against the incoming medium). Because the operating medium enters under the swivel plate, the line pressure assists in lifting the valve disc during actuation, eliminating severe fluid pressure shocks.

Flow Direction Specification

Flow direction below the seat is suitable for liquids, steam, and gases. Closing against the medium prevents line water hammer.

Operating Restriction

Do not use valves configured with flow direction above the seat for liquid media. Incompressible liquid flow over the seat causes severe hydraulic water hammer during closing, leading to ruptured piping or destroyed valve components.

Component Materials and Mechanical Design

The construction combines high-grade austenitic cast stainless steel CF3M for the body, forged 316/316L stainless steel internals, and an electropolished 1.4561 (316Ti) actuator body with an impact-resistant PPS actuator cover.

Item No.	Element	Material
1	Ground terminal	Stainless steel 1.4301 / 1.4305 (only for ATEX variant)
2	Optical position indicator	Polysulfone (PSU)
3	Pilot air ports	Polypropylene (PP) push-in connector; stainless steel 1.4305 G 1/8" on request
4	Actuator cover	Polyphenylene sulphide (PPS)
5	Actuator casing	Stainless steel 1.4561 (316Ti)
6	Piston seal	Fluoroelastomer (FKM)
7	Spring assembly	Stainless steel 1.4310
8	Actuator pipe	Stainless steel 1.4401 (316) / 1.4404 (316L)
9	Packing gland	PTFE V-rings (filled), with spring compensation
10	Valve spindle	Stainless steel 1.4401 (316) / 1.4404 (316L)
11	Spindle guide	Polyetheretherketone (PEEK)
12	Body seal	Graphite (PTFE optional)
13	Swivel plate	Stainless steel 1.4401 (316) / 1.4404 (316L)
14	Seat seal	PTFE (PEEK optional)
15	Valve body	Cast stainless steel CF3M

The spindle seal utilizes self-adjusting PTFE V-rings backed by spring compensation, maintaining stem seal integrity without manual tightening. All internal lubricants for the packing gland and actuator are classified according to NSF H1.

Technical Performance and Fluidic Data

For BURKERT 345758, the internal fluidic path is sized at DN15 with a 15 mm seat orifice, yielding a water flow factor (Kv) of 5.3 m³/h (measured with water at +20 °C and 1 bar pressure differential).

Operational Parameter	Value
Nominal Diameter (Port Size)	DN 15 / NPS 1/2
Port Connection	NPT 1/2 internal thread (ASME B1.20.1)
Actuator Size	Ø 50 mm (Size D)
Control Function	CFA (normally closed by spring force)
Flow Direction	Below seat (flow to open)
Water Flow Coefficient ($K_v$)	5.3 m³/h
Minimum Pilot Pressure	5.2 bar(g)
Maximum Pilot Pressure	10.0 bar(g)
Maximum Operating Pressure (PTFE Seal)	25.0 bar(g)
Maximum Operating Pressure (PEEK Seal)	25.0 bar(g)
Seat Leakage Class	Rate A (DIN EN 12266-1)
Maximum Fluid Viscosity	600 mm²/s

Dimensions and Installation Geometry

BURKERT 345758 features an installation face-to-face body length (LM) of 65 mm. The actuator can be installed in any orientation, preferably upright.

Actuator Dimensions Across Series

DN	NPS	Actuator Size Ø	Ø A [mm]	B [mm]	H [mm]	K/M [mm]
15	1/2	50 (D)	64.5	166	163	147
15	1/2	70 (M)	91.0	182	178	156
20	3/4	50 (D)	64.5	174	171	155
20	3/4	70 (M)	91.0	189	186	163
25	1	50 (D)	64.5	175	173	156
25	1	70 (M)	91.0	191	188	165
25	1	90 (N)	120.0	229	228	203
32	1 1/4	70 (M)	91.0	201	197	174
40	1 1/2	70 (M)	91.0	204	201	178
50	2	70 (M)	91.0	223	219	196

Note: Dimensions B, H, K, and M are maximum dimensions and may be up to 6 mm less depending on the specific connection standard.

Threaded Body Dimensions (G, NPT, RC)

DN	NPS	E (G) [mm]	E (NPT) [mm]	E (RC) [mm]	CM [mm]	LM [mm]	AF [mm]
8	1/4	14.0	10.0	9.7	24.0	75	—
10	3/8	12.0	10.3	10.1	24.0	65	27
15	1/2	14.0	13.7	13.2	24.0	65	27
20	3/4	16.0	14.0	14.5	27.0	75	34
25	1	18.0	16.8	16.8	29.5	90	41
32	1 1/4	16.0	17.3	19.1	36.0	110	50
40	1 1/2	18.0	17.3	19.1	35.0	120	55
50	2	24.0	17.6	23.4	45.0	150	70
65	2 1/2	26.0	23.7	26.7	57.0	185	85
80	3	28.0	—	—	71.0	220	100

Pressure and Temperature Derating Limits

Operating pressures must be derated when operating near maximum medium temperatures in accordance with DIN EN 12516-1 and ASME B16.34 standards.

Operating Limits According to Pressure Standards

Temperature [°C]	DIN EN 12516-1 (PN25) [bar]	ASME B16.34 Cl. 150 [bar]	JIS B 2220 10K [bar]
-29 to +38	25.0	19.0	14.0
-10 to +50	25.0	18.4	14.0
+100	24.5	16.2	14.0
+150	22.4	14.8	13.4
+185	21.0	14.1	12.8
+200	20.3	13.7	12.4
+230	19.0	12.7	11.7

For pilot air port connections, when using the standard push-in connector, the permitted ambient temperature range is -10 °C to +60 °C. With threaded bushings, the ambient limit reaches +100 °C.

Decentralized Automation Combinations

BURKERT 345758 integrates directly into modular ELEMENT valve automation systems:

• Type 8691 Control Head: Features contactless inductive valve position detection, integrated pilot valves, high-luminosity color status LEDs, and teach-in automatic end-position detection. Designed for actuator sizes Ø 70 mm to Ø 130 mm.
• Type 8695 Control Head: Compact automation unit tailored for actuator size Ø 50 mm (D). Features integrated pilot valve with manual override, optical/electrical feedback, AS-Interface, IO-Link, and büS communication.
• Type 8690 / Type 8697 Pneumatic Control Units: Mechanical or inductive limit switches for integrated end-position feedback and pilot air control. Type 8697 matches the Ø 50 mm actuator size.
• Type 8801-YE Automation System: Completely tested, factory-assembled valve packages combining Type 2100 valves with 869x control units.

Installation and Assembly Instructions

Observe pipeline alignment and flush all piping upstream to prevent foreign particles from damaging the seating surface.

Rotating the Actuator Assembly

The pilot air connections can be rotated 360° to facilitate hose routing:

1. Secure the valve body firmly in a holding fixture.
2. Open the valve: For Control Function A, pressurize pilot air port 1 with compressed air (minimum 5.0 bar) to lift the swivel plate off the valve seat before turning.
3. Position an open-end wrench on the hexagon flats of the actuator connection joint while holding the valve body connection flats with a second wrench.
4. Rotate the actuator exclusively in the clockwise direction indicated in the figure until reaching the target alignment.

Avoid Joint Loosening

Rotating the actuator counter-clockwise risks loosening the central body thread, compromising sealing and allowing process media to escape under pressure.

Actuator Body Connection Tightening Torques

When reattaching the pneumatic actuator to the valve body, lubricate the threads with Klüber paste UH1 96-402 and observe the specified torque values.

Nominal Diameter	Actuator Size	Tightening Torque [Nm]	Tolerance [Nm]
DN 15	50 (D)	45	+10 / -5
DN 20	50 (D), 70 (M)	50	+10 / -5
DN 25	50 (D), 70 (M), 90 (N)	60	+10 / -5
DN 32	70 (M), 90 (N), 130 (P)	65	+10 / -5
DN 40	70 (M), 90 (N), 130 (P)	65	+10 / -5
DN 50	70 (M), 90 (N), 130 (P)	70	+10 / -5
DN 65	90 (N), 130 (P)	70	+10 / -5
DN 80	130 (P)	120	+10 / -5

Maintenance and Troubleshooting

Regular visual inspection verifies external tightness and mechanical operating integrity.

Leakage Inspection Points

Inspection Checkpoint	Observed Defect	Required Corrective Action
Media Connectors (1)	Medium leakage at pipeline joint	Reseal or repair pipe threading connections
Relief Bore (2)	Medium or pilot air leakage at relief port	Replace spindle packing gland or actuator assembly
Swivel Plate / Seat (3)	Downstream leakage through valve seat	Clean seat surface or replace internal swivel plate set

Troubleshooting Guide

Fault Condition	Potential Root Cause	Corrective Procedure
Actuator does not switch	Pilot air port inverted	Connect pilot pressure correctly to port 1 for CFA
	Pilot air pressure insufficient	Verify pilot air supply delivers minimum 5.2 bar(g)
	Operating medium pressure exceeds limit	Check that operating pressure is within 25 bar limit
	Medium flow reversed	Reinstall valve matching the flow direction arrow
Valve does not seal tightly	Debris trapped between seal and seat	Dismantle, flush pipeline, and install upstream strainer
	Worn or scored PTFE seat seal	Replace swivel plate assembly using factory kit
Medium leaks at relief bore	Spindle packing gland seals worn	Replace packing gland using socket wrench 683221

Packing Gland Service Tool

Replacement of the internal spindle packing gland requires factory socket wrench Article No. 683221 (for 10 mm spindle, AF 19 mm, covering DN15 to DN50).