Siemens VGD4/VRD4 Double Gas Valve with SKPx5 Actuators

Introduction

This document provides operation and mounting instructions for the Siemens VGD4/VRD4 double gas valve combined with SKPx5 actuators. It details the functions, applications, installation, and technical specifications of these components, primarily intended for gas-fired combustion plants.

Note: The combination of a VGD4/VRD4 double gas valve with a QPLx5 pressure switch and SKPx5 actuator does not require any maintenance.

Caution: This document is intended for end users. All legal, safety, warning, and technical notes contained in the data sheets for the SKPx5 actuator (N7643), VGD4 double gas valve (N7631), VRD4 double gas valve for biogases and recycling gases (N7649), and the QPLx5 pressure switch (N7221) are also applicable.

1 Use

The combination of the SKPx5 actuator and VGD4/VRD4 double gas valve functions as:

• Safety shutoff valve (SKP15)
• Safety shutoff valve with specific pressure control (SKP25)

1.1 SKP15 actuator

The electrohydraulically operated SKP15 gas fittings, when used with VGD4/VRD4, function exclusively as a safety shutoff valve (OPEN/CLOSED). They are primarily used on gas-fired combustion plants, opening slowly and closing rapidly. The SKP15 actuator can be supplied with end switches and a valve stroke display, or without these features.

1.2 SKP25 actuator

The electrohydraulically operated SKP25 gas fittings, when used with VGD4/VRD4, function as a safety shutoff valve (OPEN/CLOSED) and also as a gas pressure governor. This controls the gas pressure on the outlet side according to a setpoint established by a setpoint spring. The SKP25 actuator can be supplied with or without an end switch. The valve stroke display is generally provided.

1.3 Application example

Diagrams illustrate the combination of VGD40/VRD40 with SKP15 and SKP25 actuators, showing configurations with and without valve stroke display and end switches.

2 Description of the SKPx5 actuators

2.1 Electrical connection

The SKPx5 actuator can be activated by 120 V~ or 230 V~. Diagrams show the electrical connections for AGA64 and AGA65, including potential-free end switches for indicating the fully closed position.

2.2 SKP15 actuator

The SKP15 actuator features a valve stroke display (1), indication of operating state via LED (2), power supply connection (3), and an end switch for valve CLOSED status (4). A timing diagram shows the valve stroke over time. Service note: No spare parts are available for the SKP15 actuator; the entire unit must be replaced by contacting the burner manufacturer.

2.3 SKP25 actuator

The SKP25 actuator includes a valve stroke display (1), operating state LED (2), power supply (3), end switch (valve CLOSED) (4), setpoint spring setting (5), assembly of the AGA25.2 damping throttle (6), and gas connection (7). A timing diagram illustrates pressure control. Service note: Similar to the SKP15, spare parts are not available, and replacement requires contacting the burner manufacturer. Note: The vent opening (6) must not be closed or clogged.

2.4 Description of the VGD4/VRD4 double gas valve

Work on the VGD4/VRD4 double gas valve should only be performed by qualified personnel. Specifications include maximum operating pressure (Pmax = 100 kPa for DN 40/50, Pmax = 70 kPa for DN 65-150), ambient temperature range (-15 to +60°C), suitability for <60°C air, and compliance with EN 161 (Valve 1 + Valve 2, Class A, Group 2). It features a built-in filter with a mesh size of 0.9 mm.

2.5 Mounting position

Diagrams illustrate recommended mounting positions for the valve combination, including protection against weather with the AGA66 gasket set, which increases the degree of protection from IP54 to IP65.

2.6 Torques

Tables specify the maximum torques for flange connections and stud screws according to DIN 939, as well as the maximum torque for pressure connections (M4, G1/8, G1/4, G3/4).

2.7 Installation dimensions

A detailed table provides installation dimensions (A through H2) for various VGD4/VRD4 models (DN 40 to 150) when combined with SKPx5 actuators. VGD40.xxxL double gas valves are supplied with reverse-mounted connecting plates.

2.8 Pressure connections

Diagrams show the pressure connections for VGD40/VRD40 and VGD41 models, including pilot gas connecting plates (AGA40.40, AGA40.41) and pressure switch connecting plates. A key defines the pressure points: pi (inlet pressure), pm (pressure between valve V1/V2), and po (outlet pressure for valve V2). A note advises removing M4 locking screws as needed.

3 Description of the mountable QPLx5 pressure switches

The QPLx5 pressure switch monitors gas pressure, opening or changing over electrical circuits when pressure falls below or exceeds a set point. Caution/Service note: The QPLx5 should be replaced when replacing a valve, ideally after 50,000 cycles or 10 years of service life, as per AFECOR recommendations. Reinstallation is not recommended, even if seals are replaced. Diagrams illustrate connections for QPL25 and QPL15 pressure switches, showing pi, pm, and po points. Attachment options include configurations with multiple pressure switches and valve proving controls.

4 Connection diagram

4.1 Function as a minimum/maximum pressure switch

Diagrams illustrate the function of minimum and maximum pressure switches, showing how NO (Normally Open) and NC (Normally Closed) contacts behave relative to the set pressure value.

4.2 Connection via connector AGA65 according to DIN 43650

A diagram shows the connection layout for the AGA65 connector, indicating COM, NO, and NC terminals.

5 Technical data

5.1 SKPx5 actuator

Environmental conditions: Climatic: Class 3K3; Mechanical: Class 3M3; Temperature range: -10 to +60°C (with potential for longer opening times below 0°C, or -20 to +60°C with heating element AGA63.5A27); Humidity: <95% r.h.; Installation altitude: Max. 2,000 m above sea level.

5.2 VGD4/VRD4 double gas valve

Environmental conditions: Climatic: Class 3K5; Mechanical: Class 3M2; Temperature range: -10 to +60°C; Humidity: <95% r.h.; Installation altitude: Max. 2,000 m above sea level. Note: Refer to the SKPx5 actuator nameplate for the VGD4/VRD4 model number.

5.3 QPLx5 pressure switch

Environmental conditions: Climatic: Class 3K5; Mechanical: Class 3M2; Temperature range: -15 to +60°C; Humidity: <95% r.h. Caution: Condensation, formation of ice, and ingress of water are not permitted.

6 Spare parts and accessories

A table lists various spare parts and accessories for the VGD4/VRD4 double gas valves and SKPx5 actuators, including article numbers and types:

• Adapter plug (BPZ:AGA62.000A000)
• Contact box for valve actuator (power supply) (BPZ:AGA64)
• Contact box for end switch (BPZ:AGA65)
• Heating element (BPZ:AGA63.5A27)
• Gasket set (BPZ:AGA66)
• Damping throttle for the SKP25 actuator (BPZ:AGA25.2)

Additional items include setpoint springs (yellow/gold, red, unpainted) for the SKP25 actuator with specific kPa ranges and diameters, and AGA30.x setpoint fine adjustment kits.

7 Lifetime

The VGD4/VRD4 double gas valve and SKPx5 actuator combination has a design lifetime based on burner startup cycles:

• <DN 25: 200,000 cycles
• DN 25...80: 100,000 cycles
• DN 80...150: 50,000 cycles

This is based on endurance tests specified in EN 161 and conditions published by the European Control Manufacturers Association (Afecor) (www.afecor.org). After reaching the designed lifetime, the components must be checked and/or replaced by authorized personnel. Tightness testing criteria are in EN 161 / EN 13611. A table summarizes the structural lifetime of safety components: Gas pressure monitor (10 years), Double gas valve with valve proving system (50,000 cycles / 10 years), and Double gas valve without valve proving system (50,000-200,000 cycles / 10 years).

* The designed lifetime is not the warranty time specified in the Terms of Delivery.