DM1 Series C Double Valves Installation Instructions — Basic Size 2, 4 & 8

Overview

The ROSS Controls DM1 Series C is a premium-quality control-reliable pneumatic double valve featuring dynamic monitoring for Category 3 and 4 safety applications. Monitoring and air flow control functions are integrated into two identical valve elements, providing Cat. 4 performance within a single, compact package. The valve exhausts downstream air if asynchronous movement of valve elements occurs during actuation or de-actuation, resulting in a residual outlet pressure of less than 1% of supply.

Unlike the DM2® Series C which requires an intentional reset following lockout, the DM1 Series C uses automatic reset — if the abnormal condition clears, the valve returns to the ready-to-run state without requiring a dedicated reset signal. This behavior is known as "automatic reset" and makes the DM1 Series C appropriate for applications where the control system can detect and manage momentary fault conditions. An optional status indicator is strongly recommended to ensure any transient lockouts are not missed during machine operation.

The DM1 Series C is designed for base mounting in Basic Sizes 2, 4, and 8. It is not for use in press clutch/brake applications — the DM2® Series D is designed for those uses. ROSS Controls, founded in 1921, has been manufacturing fluid power safety products for over 100 years.

Key Features

Dynamic Monitoring with Integrated Dual Valve Elements

The DM1 Series C integrates dynamic monitoring directly into its two identical valve elements. Each element monitors the other in real time during actuation and de-actuation. If one element fails to shift fully within the discordance time window, the valve takes fail-safe action by exhausting downstream pressure through Port 3, reducing outlet pressure to less than 1% of supply.

Automatic Reset Operation

The DM1 Series C does not use memory-based lockout like the DM2® Series C. When a fault condition clears — for example, when both pilot solenoids are de-energized and the valve elements return to their correct positions — the valve automatically returns to the ready-to-run state. This "automatic reset" behavior simplifies machine control logic but requires the optional status indicator to be used so that momentary faults are not missed.

Status Indicator with Pressure Switch Feedback

The optional status indicator utilizes a pressure switch with four electrical contacts to signal machine controls that a lockout has occurred. During normal operation, the pressure switch is pressurized. A lockout condition depressurizes the switch until the valve returns to ready-to-run state. Contacts 1 and 2 are normally closed (switch depressurized); contacts 1 and 3 are normally open (adequate pressure signal applied).

Technical Specifications

Safety Category: Category 3 and 4 per ISO 13849-1
Construction Design: Dual poppet
Basic Sizes: BG 2, BG 4, BG 8
Overall Function: 3/2 (three-port, two-position) normally closed
Actuation: Dual solenoid pilots — both must be energized simultaneously
Reset Type: Automatic reset (de-energize both solenoids to clear fault)
Discordance Detection: Approximately 125 milliseconds preset
Residual Outlet Pressure in Lockout: Less than 1% of supply pressure
Exhaust: Factory-equipped with ROSS silencer (noise reduction up to 25 dB)
Electrical Connection: Plug-in connectors
Standard Voltages: 24 VDC; 110–120 VAC, 50/60 Hz
Flow Media: Filtered compressed air
Mounting: Base mounting
Application Limitation: Not for press clutch/brake applications

Applications

Category 3 and 4 Pneumatic Machine Safety

The DM1 Series C is designed for Category 3 and Category 4 machine safety applications including pneumatic clamping systems, automated assembly equipment, material handling systems, and any pneumatic safety circuit requiring redundant valve monitoring. Its compact basic size range (BG 2, 4, 8) makes it suitable for space-constrained machine installations.

Applications Requiring Automatic Reset

Applications where the machine control system can reliably detect and manage momentary faults, and where an optional status indicator is used to capture transient lockouts, are well-served by the DM1 Series C. The automatic reset capability reduces downtime in applications where intermittent fault conditions are acceptable within the overall safety strategy.

Safety and Compliance Standards

ISO 13849-1 — Category 3 and 4 compliance
Dynamic monitoring integrated into both valve elements
Optional status indicator for lockout feedback to machine controls
Not for mechanical power press clutch/brake applications (use DM2® Series D)
Lubrication: Not required — valve does not require air line lubrication
Compatible lubricants (for other mechanisms): Petroleum base oils, ISO 32 or lighter, aniline point 180°F–220°F (82°C–104°C), oxidation inhibitors

Installation and Setup Guide

Air Line Preparation

Before installing in a new or existing system, blow all air lines clean of contaminants. Install a 5-micron rated air filter in the inlet line close to the valve.

Valve Inlet — Port 1

Ensure the supply line is of adequate size without restrictions (crimps, sharp bends, or clogged filter elements). The air supply must provide sufficient pressure and adequate flow on demand. Insufficient supply will cause the valve elements to be momentarily starved for air and may cause erratic operation.

Valve Outlet — Port 2 and Exhaust — Port 3

Locate the valve as close as possible to the mechanism being controlled to minimize pressurizing and exhausting time. Do not restrict air flow from the exhaust port — restriction adversely affects valve operation. The valve is factory-equipped with a ROSS silencer that reduces exhaust impact noise by up to 25 dB with minimal back pressure.

DM1 Series C Testing Procedure

After installation: (A) Energize both solenoids — Port 1 should supply Port 2, no flow to Port 3. (B) De-energize one solenoid — valve should lock out, exhausting Port 2 to Port 3. (C) Re-energize that solenoid — valve must remain in lockout. (D) De-energize both solenoids — valve should return to ready-to-run state. (E–H) Repeat B–D for the other solenoid. After passing all tests, normal operation may proceed.

Why Choose ROSS Controls

ROSS Controls has been engineering pneumatic safety solutions for over 100 years. The DM Series C reflects continuous innovation in double valve technology, providing machine builders with certified, reliable, and easy-to-install safety valve solutions. ROSS's global distributor network and technical support team ensure you have access to expert assistance wherever you operate. Contact ROSS at 1-800-GET-ROSS or www.rosscontrols.com.

Download This Document

The official DM1 Series C Double Valves Installation Instructions (document SS306) covers Basic Sizes 2, 4, and 8. Download the complete PDF for full valve specifications, test procedures, and service kit information.

Download PDF: https://ross-admin-global-us-east.s3.amazonaws.com/production/uploads/document_language_file/file/60/ROSS_DM1_Series_C_Double_Valves_Installation_Instructions_SS306.pdf.pdf

Frequently Asked Questions

Q: What is the key difference between DM1 Series C and DM2® Series C?

A: The DM1 Series C uses automatic reset — once the fault clears and both solenoids are de-energized, the valve automatically returns to ready-to-run. The DM2® Series C requires an intentional reset signal after any lockout. DM2® Series C is preferred where it is critical that any fault be formally acknowledged before resuming operation.

Q: What happens to downstream pressure when DM1 Series C locks out?

A: When a lockout occurs, any downstream pressure at Port 2 is exhausted to atmosphere through Port 3. The residual outlet pressure drops to less than 1% of supply pressure, and a small audible air flow continues from the exhaust until the valve returns to ready-to-run.

Q: Is the DM1 Series C suitable for press clutch/brake applications?

A: No. Due to its automatic reset characteristics (Category 4, not for press applications), the DM1 Series C must not be used to control press clutch/brake mechanisms. ROSS Controls produces the DM2® Series D specifically for mechanical power press applications.

Q: What basic sizes are available for the DM1 Series C?

A: The DM1 Series C is available in Basic Sizes 2, 4, and 8, covering a range of flow capacities for different machine sizes and pneumatic circuit requirements.

Q: How does the status indicator pressure switch work?

A: The status indicator has four electrical contacts. During normal operation, the switch is pressurized: contacts 1 and 3 are closed (normally open). During a lockout, the switch depressurizes: contacts 1 and 2 close (normally closed). This signal can be fed to machine controls to indicate a fault condition.

Q: Does the DM1 Series C require air line lubrication?

A: No. The DM1 Series C double valve itself does not require air line lubrication. However, if lubricated air is supplied to other mechanisms in the circuit, use compatible petroleum base oils with ISO 32 or lighter viscosity and avoid oils with phosphate additives or diester oils.

Q: How much noise reduction do ROSS silencers provide?

A: ROSS silencers can reduce exhaust impact noise by as much as 25 dB, with minimal back pressure. The DM1 Series C is factory-equipped with a properly sized ROSS silencer.

Q: What is the discordance detection time for DM1 Series C?

A: The internal monitoring detects asynchronous valve element movement within approximately 125 milliseconds. This timing is preset by restricting orifices and chambers in the pilot air circuit and is not field-adjustable.