Siemens VGD40.080 Gas Double Valve Body

Flanged gas double valve body (body only, without SKP actuators). It belongs to the Siemens VGD40 series gas safety shut-off valve bodies, used for gas safety cut-off in industrial burners, boilers and industrial furnaces. It must work together with SKP series hydraulic actuators.

✅ Model Definition

VGD40: Cod de serie, flanged double-spool gas valve body

080: Nominal diameter DN80

Standard designation: VGD40.080, not VGD40-080

📌 Core Technical Parameters

1. Diametrul nominal: DN80, PN16 flange (ISO7005-2)
2. Valve Body Structure: Double spools with double springs for dual-channel safety shut-off, compliant with EN298 gas safety standard. Pressure test ports are integrated on the valve body for valve train leak test and pressure monitoring.
3. Mediu: Natural gas, town gas, liquefied petroleum gas (clean fuel gas; VRD series is required for biogas with high sulfur content)
4. Pressure Ratings

Max shut-off pressure: 1500 mbar

Max continuous operating pressure: 700 mbar

5. Ambient / Temperatura medie: -10℃ ~ +60℃
6. Volume of V1/V2 Intermediate Chamber: aproximativ. 1.9 L
7. Material: Cast aluminium valve body
8. Actuatori compatibile: SKP15 (safety shut-off + slow opening), SKP25 (reglarea presiunii), SKP55 (differential air/gas ratio), SKP75 (static pressure air/gas ratio)

📊 Flow Reference (Natural gas, 0℃, 1013 mbar)

480 m³/h → Burner output 4858 kW, pressure drop across valve train 34 mbar

640 m³/h → Burner output 6477 kW, pressure drop across valve train 57 mbar

800 m³/h → Burner output 8096 kW, pressure drop across valve train 90 mbar

Sizing hint: If pipeline velocity＞35 m/s, it is recommended to increase pipe size downstream to reduce noise and erosion.

🔧 Typical Valve Train Configuration (Upstream to downstream)

Gas filter → Pressure switch (QPL) → VGD40.080 body + SKP actuators → Downstream pressure switch → Burner

Burner controller: LME / LMV series, supporting automatic valve train leak test

⚠️ Installation & Note de întreținere

1. Orientarea montajului: Valve body can be installed horizontally or vertically, actuator must NOT face down. Gas flow direction must match the arrow marked on valve body.
2. A gas filter must be installed upstream to protect spool seals from contaminants.
3. Perform periodic valve train leak test (LME/LMV controllers have built-in leak test sequence). Over-limit leakage requires overhaul of spool seals.
4. Isolate upstream ball valve and release pressure before maintenance. Do NOT disassemble actuators under pressure.
5. If leak test fails or valve cannot seal properly, inspect spool and seals first; then check hydraulic oil of SKP actuator.

🛠️ Troubleshooting (VGD40.080 valve body side)

1. Excessive leakage when closed: Aged rubber seals on spool, foreign debris stuck; clean or replace seal assembly.
2. Insufficient flow / high pressure drop: Clogged filter or fouled valve cavity.
3. Leakage at pressure test ports: Aged gasket of test nozzle.

Nota: Failure to open or slow opening is mostly not valve body fault, but SKP actuator failure (hydraulic oil or coil).

📎 Alternatives & Aceeași serie

Aceeași serie: VGD40.065 (DN65), VGD40.100 (DN100)

Small size threaded type: VGD20 series

Gas containing hydrogen sulfide: VRD40.080

📌 Supplementary

VGD40.080U: UL certified North American version with slightly different pressure parameters

No solenoid coil fitted on valve body. SKP is the driving unit. SKP is often omitted during procurement.

VGD40.080 + SKP25 Bill of Material & P&ID Description

Aplicație: Gas combustion system for industrial boilers / hot blast furnaces, double safety shut-off + constant downstream gas pressure regulation, compatible with automatic valve leak test via burner controller. Two SKP actuators are required for VGD40 double valve body: upstream V1 valve with SKP15 (safety shut-off + slow opening), downstream V2 valve with SKP25 (reglarea presiunii).

1. Complete Valve Train BOM (DN80)

Procurement reminder: Many buyers only purchase one SKP25. VGD40 double valve has two independent spools requiring two separate actuators.

2. P&ID Flow Description (Text version for CAD drafting)

Flow path: Natural gas main line → Manual ball valve → Gas filter LFK → High pressure switch QPL15.150 → VGD40.080 body V1 valve (driven by SKP15) → Intermediate cavity pressure tap (leak test differential pressure switch QPL15.005) → VGD40.080 body V2 valve (SKP25 pressure regulation) → Downstream pressure tap → Low pressure switch QPL15.010 → Burner

P&ID Tagging

1. PT1: Upstream gas pressure (before filter)
2. PT2: Pressure in intermediate cavity between V1 and V2 (leak test pressure)
3. PT3: Downstream gas pressure (feedback tap for SKP25 pressure regulation)
4. PS-H: High pressure interlock switch, cut-off on overpressure
5. PS-L: Low pressure interlock switch, cut-off on underpressure
6. ΔP: Differential pressure switch for valve train leak test

Logica de control

1. Standby: SKP15 and SKP25 de-energized; both valves closed by spring force
2. Pre-start: LME/LMV executes valve train leak test to check V1 and V2 internal leakage; ignition inhibited and alarm triggered if leak test fails
3. Ignition phase: SKP15 energized first, V1 opens slowly; then SKP25 energized, V2 opens gradually. SKP25 maintains low fire pressure for ignition.
4. Load regulation: SKP25 built-in pressure regulator holds constant downstream gas pressure for high fire operation
5. Shutdown / Fault interlock (flame loss, suprapresiune, pierdere de putere): SKPs de-energized, both valves shut rapidly, shut-off time＜1s
6. Electrical Wiring Notes
7. SKP15 and SKP25 supply AC220V; AC380V is strictly forbidden.
8. Solenoid inside SKP is driven by dry contact output from LME/LMV burner controller.
9. All pressure switches are passive dry contacts wired into burner safety circuit. Activation of any pressure switch cuts SKP power supply for emergency shut-off.
10. Differential pressure switch for leak test connects to controller leak test terminals.
11. Commissioning Steps for Valve Train Leak Test
12. Before gas supply: Confirm pipeline purging and flange tightness. Actuator mounting: actuator upward or horizontal, NOT downward.
13. Close downstream burner ball valve and seal downstream piping.
14. Feed gas and adjust upstream pressure to working setpoint.
15. Start valve leak test in LME controller menu:

Pas 1: V1 open, V2 closed → test leakage of V2 spool

Pas 2: V1 closed, V2 open → test leakage of V1 spool

5. Passed leak test: ignition permitted. Failed leak test: inspect spool seals, actuators and pressure tap piping for leakage.
6. Sizing Boundary Reminder

Max continuous operating pressure: 700 mbar; Max shut-off pressure:1500 mbar

Flow limit: 800 m³/h natural gas with 90 mbar pressure drop; upgrade to DN100 VGD40.100 if flow exceeds this value

Mediu: Natural gas. VRD40.080 must be used for biogas with hydrogen sulfide.

Working Principle of Siemens VGD40.080 (DN80)

Important: VGD40.080 is only the valve body without electromagnetic driving capability. The complete valve assembly consists of [VGD40.080 double valve body + 2 SKP electro-hydraulic actuators]. The valve body provides gas flow path and sealing, while SKP serves as power and control unit.

1. Structural Principle of Valve Body

VGD40.080 is a series double-seat, double-spool valve body with two independent closing springs. Two separate spools V1 (upstream) and V2 (downstream) are fitted with individual closing springs. In de-energized state, springs press spools tightly and valves remain closed, meeting EN298 safety requirement for redundant double valve.

1. V1 upstream spool (paired with SKP15): Flat spool for safety shut-off and slow opening only, no pressure regulation.
2. V2 downstream spool (paired with SKP25): Contoured spool. Besides safety shut-off, it works with SKP25 to regulate downstream gas pressure.
3. Three pressure test ports integrated on valve body: upstream port, intermediate cavity port between V1 & V2, downstream port. The intermediate cavity is used for valve train leak test to detect internal leakage of both spools.

Core safety logic: Gas can only flow to burner when both spools open simultaneously. Reset of either spring will cut off gas supply.

2. Working Principle of SKP Electro-hydraulic Actuator (Power Core)

SKP is an electro-hydraulic actuator mounted on top of VGD valve body. Valve stem pushes spool downwards against spring force to open valve:

1. De-energized state (așteptare / vina)

Solenoid valve inside SKP de-energizes, hydraulic chamber depressurizes. Valve body springs push spools upward. V1 and V2 close rapidly to cut gas supply. Fail-safe: valve closes on loss of power.

2. Energized opening (pre-ignition)

Burner controller LME/LMV sends AC220V to SKP coil. Solenoid energizes and seals hydraulic chamber. Hydraulic pressure builds up and pushes plunger downwards. Valve stem compresses spool against closing spring to open valve.

SKP15: On/off + slow opening, fixed opening stroke, no pressure regulation

SKP25: Built-in pressure feedback diaphragm, sensing downstream gas pressure as feedback, dynamically adjusts spool stroke to maintain constant downstream gas pressure.

3. Full Operating Sequence (VGD40.080 + SKP15 + SKP25)

1) Standby

SKP15 and SKP25 de-energized. V1 and V2 fully closed by spring force, gas flow blocked. Intermediate cavity pressure tap ready for leak test.

2) Pre-start: Valve Train Leak Test (executed by LME/LMV controller)

Controller performs leakage check for V1 and V2 spools:

Etapă 1: V1 open, V2 closed → test inward leakage of V2 spool

Etapă 2: V1 closed, V2 open → test inward leakage of V1 spool

Ignition will be locked and alarm triggered if leak test fails.

3) Ignition Phase

Controller outputs signal, SKP15 energized first, V1 opens slowly, gas enters intermediate cavity between V1 and V2. Then SKP25 energized, V2 opens gradually. SKP25 diaphragm senses downstream pressure and adjusts stroke automatically to maintain low-fire pressure for ignition.

4) Normal Load Operation

SKP15 remains fully open;

SKP25 continuously samples downstream gas pressure. Pressure rise → reduce spool opening; pressure drop → increase spool opening, dynamic pressure stabilization to maintain constant gas pressure for burner load variation.

5) Shutdown / Fault Interlock (flame loss, suprapresiune, pierdere de putere)

SKPs de-energized, hydraulic pressure released. V1 and V2 close rapidly under spring force within＜1s. Dual valves shut for redundant gas isolation.

4. Valve Train Leak Test Principle (Key function of intermediate cavity of VGD body)

Sealed intermediate chamber between V1 and V2 connected to differential pressure switch QPL15.005:

If V1 spool leaks, upstream gas enters intermediate cavity and cavity pressure rises;

If V2 spool leaks, downstream gas flows back into intermediate cavity;

Controller monitors pressure change in intermediate cavity to judge spool sealing performance and implement protective leak detection.

5. Key Summary
6. VGD40.080 valve body is pure mechanical double valve body without solenoid or hydraulic components. Without SKP actuators, valve body stays closed permanently.
7. Safety nature: Series double valves + spring forced closing, automatic shut-off on power loss.
8. Regulation function is fully realized by pressure feedback diaphragm of downstream SKP25 actuator. Valve body only provides gas passage and sealing.
9. Pressure test ports on valve body are mandatory for EN298 valve train leak test.