SIL Safety Manual for D, I, L Series Pneumatic Spool Valves

Purpose and Scope of the Safety Manual

The purpose of this safety manual is to describe the application of SIL-certified pneumatic Automatic Valve spool valves of the D, I, and L series in safety instrumented systems according to IEC 61508. It supplements the standard installation and maintenance guidelines for Automatic Valve pneumatic products. The manual applies to all Automatic Valve spool valves of the D, I, and L series in their defined type variants, covering 3/2, 5/2, and 5/3 way valves in closed center (CC), open center (OC), and pressure center (PC) configurations.

Applicable Standards and Documents

The safety manual must be used together with the installation and maintenance guidance for Automatic Valve pneumatic products. All services on the pneumatic spool valves must be performed by trained, instructed, and authorized personnel. The valves are certified according to IEC 61508, and the manual references IEC 61508-2 (Route 2H), IEC 61508-4:2010 for safety item definitions, and IEC 61508-6 for common cause failure (beta factor) calculations.

SIL Certification and Safety Integrity Levels

The Automatic Valve D, I, and L Series spool valves have been certified by SGS-TUV Saar in accordance with IEC 61508. In singular application with Hardware Fault Tolerance (HFT) = 0, the valves are certified to SIL 2. In redundant application with HFT greater than or equal to 1, the valves meet the requirements for SIL 3 and Performance Level e (PL e). This certification validates the valves' suitability for use as final elements in safety instrumented systems across a wide range of industrial process safety applications.

The different ordering and series codes used for D, I, and L valves describe different features such as pipe adapter size, flow rate, IP protection class, and explosion-proof ratings (EX proof). These features all rely on an identical safety principle, so the different features have no influence on the safety concept of the valves.

Safety Function and Safe State Definitions

The manual provides detailed safety function definitions according to IEC 61508-4:2010, covering safe state, safety function, process safety time, dangerous failure, dangerous detected failure, dangerous undetected failure, safe failure, no-effect failure, and fail-safe principle. These definitions establish a common understanding of failure modes critical for safety loop design.

Safety Function for Single Pilot Valves (3/2 and 5/2)

For 3/2-way and 5/2-way single pilot operation valves (solenoid or air actuation), the home position is reached by spring force without any energy supply. In case of demand of the safety function, the valve will be shut off and will reach the safe position (home position) within the specified safety time by spring force. The safe state can be normally open (NO) or normally closed (NC) depending on the valve configuration. For 3/2 NC: port 1 is blocked and port 2 exhausts via port 3 at the safe home position. For 5/2: port 1 flows to port 2, port 3 is blocked, and port 4 exhausts via port 5 at the safe home position.

Safety Function for Double Pilot Valves (5/2 and 5/3)

For 5/2-way double pilot operation valves, the valve stays in its actual position upon demand of the safety function. For 5/3-way double pilot operation valves, the valve reaches the middle position by spring force upon demand of the safety function. The middle position can be configured as block center (all ports blocked), exhaust center (port 1 blocked, cylinder ports open to exhaust), or pressure center (port 1 pressurizes cylinder ports, exhaust ports blocked). These three center positions are designated CC, OC, and PC respectively in the type code.

Valve Types, Activations, and Adaptors

The manual provides comprehensive technical detail on all valve type variants, activation methods, and available adaptors for the D, I, and L series.

Valve Types and Configurations

The D, I, L series encompasses three main valve types: 3-way 2-position valves, 5-way 2-position valves, and 5-way 3-position valves. Each type is available with pneumatic or solenoid pilot activation and in various configurations (NC, NO, CC, OC, PC). The manual includes schematics for all valve type variants and images showing the physical valves with and without pilot valve assemblies. Maximum leakage is specified at 0.6 ml/min.

Activation Options

Three activation methods are available: pneumatic control (single or double) using air end-caps with various connection threads, single solenoid pilot valve using CNOMO interfaced solenoids, and double solenoid pilot valve. The solenoid pilot valves are available in different versions to accommodate various electrical supply requirements and connector standards.

Available Adaptors

Three adaptor types are available for the D series: the speed control valve adaptor (which restricts air flow from port 2 to port 3 and port 4 to port 5, mounted between valve and manifold), the transition plate (for situations where the solenoid valve sealing face extends beyond the mounting surface), and the 90-degree mounting plate (allows horizontal installation and orientates outlets 90 degrees to the actuator). The speed control valve adaptor must never be used to delay the safety time — it is only for non-safety time delay.

Type Codes and Valid Variants for Safety Applications

The manual provides detailed type code breakdowns for all valid variants certified for safety applications. These include ISO-series valve part numbers for air piloted and solenoid operated spool valves, L-series valve part numbers for air piloted and solenoid piloted configurations, D20-series and D06-series valve part numbers, and D06/D20 special valve part numbers (D06-001, D20-018, D20-024). Each type code image shows how to read the valve designation to identify series, size, valve type, center position configuration, activation method, and options.

Common designations for the SIL-certified valves include VH for D, I, L type body, and the general series designation AV Automatic Valve Spool Valves for Line Mounting Series D, I, L. The mechanical interfaces include threads for pressure supply, bleeder, and pneumatic control, plus installation interfaces for mounting and actuation. Electrical interfaces apply when solenoid pilot valves are installed.

Safety Time, Installation, and Commissioning

The safety time — the interval from demand of the safety function until the safe state is reached — varies depending on the specific application. Main influences include forces from operating medium, environmental pressure, piping, fittings, and other installation factors. The manual provides parts movement times by series: D06 actuating 0.030s / de-actuating 0.043s, I15 actuating 0.012s / de-actuating 0.030s, I20/D20/L20/L21 actuating 0.010s / de-actuating 0.044s, and I45/L45 actuating 0.020s / de-actuating 0.055s.

Installation must follow the standard installation and maintenance guidelines for Automatic Valve pneumatic products, with special attention to safety-relevant activations (pneumatic and electrical) and adaptors. Commissioning should be performed as part of the complete safety loop, and the safety time and safety function must be verified by the user before commissioning and after defined time periods with documented results.

Proof Testing, Online Diagnostics, and Maintenance

Offline proof testing must be performed every 5 years or after 5 million cycles. The proof test is defined for each specific application and includes: execution of the functional test as in commissioning, visual inspection per maintenance guidelines, renewal or replacement of malfunctioning components, additional functional testing before re-commissioning, and verification of safety time. The machine or plant must be in standstill and secured against unintentional restart during proof testing.

No online diagnostics are provided for the D, I, L series valves. Online diagnostics must be implemented by the integrator, user, or OEM in accordance with applicable standards. Inspection, repair, and maintenance must follow the installation and maintenance guidelines, with fault analysis and troubleshooting per the troubleshooting chapter. No changes affecting the safety concept or safety function may be made during service. Safety-relevant faults must be reported to the manufacturer.

Safety-Related Parameters and Architecture

Appendix B of the manual contains the safety-related parameters for the AVI spool valves, including reliability data for 1oo1 architecture (HFT = 0) and 1oo2 architecture (HFT = 1). For redundant architectures with HFT greater than or equal to 1, a beta factor (common cause failure rate) of 5% must be considered. The beta factor calculation depends on the safety-relevant architecture using the MooN table provided in the manual.

When AVI spool valves are used with valves from other manufacturers in safety architectures, the beta factor must be determined according to IEC 61508-6. The pneumatic supply system (process gas, oiling, dehydration, filters, conditioning) is not included in the valve's safety-related parameters and must be evaluated separately if it is safety-relevant in the application's safety loop.

User Responsibilities and Manufacturer Return Process

The manual clearly delineates user responsibilities for safety applications: proper valve usage according to intended use, correct installation per guidelines, ensuring operating medium purity and lubricant quality, meeting technical data sheet requirements, providing proper electrical control of pilot valves, supporting shutoff of pneumatic or electrical control signals per safety requirements, verifying safety time and safety function before commissioning and periodically thereafter, and documenting functional test results.

Appendix A includes a return form for manufacturer inspection that captures sender information, type designator, operating hours, cycle count, description of fault, and the requested action (testing, repair, or diagnosis with consultation). The manufacturer address for safety queries is Automatic Valve Industrial LLC, 950 Woodward Heights, Ferndale, Michigan 48220, USA (email: av@automaticvalve.com).

Frequently Asked Questions

What SIL rating do the Automatic Valve D, I, L Series spool valves achieve?

The D, I, L Series spool valves are certified by SGS-TUV Saar to IEC 61508 Safety Integrity Level 2 (SIL 2) when used in singular application with Hardware Fault Tolerance (HFT) = 0. In redundant application with HFT of 1 or greater (such as 1oo2 architecture), the valves achieve SIL 3 with Performance Level e (PL e). The specific safety-related parameters for use in safety loop calculations are provided in Appendix B of the safety manual.

How often must proof testing be performed on D, I, L Series valves in safety applications?

Offline proof testing must be performed every 5 years or after 5 million cycles, whichever comes first. The proof test must be conducted with the machine or plant in standstill, secured against unintentional restart. Testing includes functional testing, visual inspection, component replacement as needed, and verification of the safety time. Proof tests must be carried out by the manufacturer or qualified personnel, and results must be documented.

Can the speed control valve adaptor be used to adjust the safety time?

No — the speed control valve adaptor must never be used to adjust or delay the safety time. The manual explicitly states that this adaptor may only be used to delay the non-safety time. Using it to extend the safety time would compromise the safety function and violate the conditions of the SIL certification. The adaptor restricts air flow from port 2 to port 3 and port 4 to port 5, and is mounted between the valve and the manifold.

What is the beta factor for redundant safety architectures using these valves?

The internal beta factor for common cause failure is 5% (beta-int = 5%) for AVI spool valves used in safety architectures with HFT of 1 or greater. This value applies when combining identical AVI spool valves. When combining AVI spool valves with valves from other manufacturers, the beta factor must be determined separately according to IEC 61508-6. The pneumatic supply system shared between redundant valves must also be evaluated as a potential common cause and considered separately in safety loop calculations.

What are the parts movement times for the different D, I, L Series valve sizes?

Parts movement times vary by series. For actuating: D06 is 0.030 seconds, I15 is 0.012 seconds, I20/D20/L20/L21 is 0.010 seconds, and I45/L45 is 0.020 seconds. For de-actuating (spring return): D06 is 0.043 seconds, I15 is 0.030 seconds, I20/D20/L20/L21 is 0.044 seconds, and I45/L45 is 0.055 seconds. The total safety time for a specific application depends on additional factors including operating medium forces, piping, fittings, and other installation variables.