Burkert 20084984 Type 2934 manually operated diaphragm valve consists of a manually operated actuator, a PTFE/EPDM diaphragm, and a stainless steel T-valve body. The manual actuator features a PPS (Polyphenylene sulphide) handwheel and diaphragm bonnet, ensuring reliable use in hygienic or aggressive ambient conditions. The flow-optimised T-valve body with minimum dead space enables high flow values and a wide range of possible applications in the food, beverage, biotechnology, and pharmaceutical industries.

The actuator has a compact, autoclavable design and is equipped with an integrated visual position indicator, a reproducible stroke scale, and an adjustable minimum stroke limiter (closing limiter). The valve is CIP and SIP capable, meeting stringent hygiene requirements.

Approvals and Conformities

• FDA: The PTFE/EPDM diaphragm complies with the Code of Federal Regulations published by the FDA.
• USP: The diaphragm is tested according to United States Pharmacopeial Convention (USP) Class VI.
• EC Regulation 1935/2004: Suitable for use with food and beverages.
• Explosion Protection (ATEX/IECEx): As a category 2 device, suitable for zone 1/21 and zone 2/22 (Ex h IIC T4...T2 Gb / Ex h IIIC T135 °C...T300 °C Db).

Explosion Hazard due to Electrostatic Charge

If statically charged devices or persons discharge suddenly, there is an explosion risk in the Ex area. Take appropriate measures to ensure no electrostatic charge can build up. Clean device surfaces only by wiping gently with a damp or antistatic cloth. Ground the actuator and valve body.

Materials

No.	Element	Material
1	Handwheel	Polyphenylene sulphide (PPS)
2	Visual position indicator	Polyamide (PA) / Stainless steel 1.4305
3	Valve spindle	Stainless steel 1.4305
4	Diaphragm bonnet	Polyphenylene sulphide (PPS)
5	Diaphragm	PTFE with EPDM backing membrane
6	Valve body	Stainless steel block material 1.4435 (DIN EN 10088) / 316L (ASTM A479)

Function and Position Indicator

By manually overriding the handwheel, the force is transmitted via a spindle and the valve is opened or closed. Turning the handwheel anticlockwise opens the valve, turning it clockwise closes it.

Turning the handwheel counterclockwise reveals the yellow position indicator and the scale marked on it as the valve opens further. The stroke scale shows the relative position of the valve and serves as a fixation point for determining the rotation position.

Installation

Installation Position of T-Valve Body

The following installation positions are recommended for the installation of the T-valves in circular pipelines to ensure proper draining and functionality:

Welding Preparations

To prevent damage, dismantle the actuator and diaphragm before welding the valve body into the pipeline. Rotate the handwheel counterclockwise until it comes to a stop (OPEN position), loosen the fastening screws crosswise, and remove the actuator with diaphragm from the valve body.

Setting Minimum Stroke Limit

A minimum stroke limit can be set for the Type 2934. This setting also serves as a closing limiter to protect the diaphragm. A hexagon nut is used to do this.

1. By turning the handwheel clockwise, the valve is moved to the closed position.
2. Loosen the screw on the handwheel (hexagon socket, width across flats 2) and remove the handwheel.
3. Screw the hexagon nut as far as it will go. Minimum stroke is set.
4. Mount the handwheel on the actuator. The square on the spindle and the hexagon head of the nut must be correctly aligned.
5. Tighten the screw on the handwheel with 0.9 Nm.

TIP

Do not screw the hexagon nut in the area of the square. Only use the minimum stroke limit in the 0…25 % opening stroke range.

Maintenance and Tightening Torques

When used in accordance with the operating instructions, the actuator of the diaphragm valve is maintenance-free. After the first steam sterilisation, or when required, retighten the fastening screws crosswise.

Tightening torques for the screws (Diaphragm size 25, PTFE/EPDM):

• Tightening torque: 6 Nm (A tolerance of +10 % applies).
• Tighten each fastening screw in 3 stages (approx. 1/3, approx. 2/3, 3/3 of the tightening torque) crosswise. The diaphragm should be positioned and pressed evenly around the actuator and valve body.

Maximum permissible tightening torque for the handwheel: Turn the handwheel only until you can feel the valve closing. Do not tighten any further, as the diaphragm may be damaged. For diaphragm size 25 with PTFE at 10 bar static pressure, the maximum tightening torque is 3.5 Nm.