Providing Safety
Monitored safety valves

Why use a safety valve with electrical monitoring?

When hydraulic or pneumatic pressure drops, this can lead to unexpected movements with a risk of injury, which is why these systems, like electrical systems, must be designed safely and redundantly

Complies with
Cat. 4/PLe

Hydraulic and

Fluidsentry by Fortress

Safety valves with electrical monitoring

Fluidsentry from Fortress offers a range of highly secure pneumatic and hydraulic electrically monitored safety valves, specially designed for Cat. 4, PLe, and SIL3 applications.

HSV Hydraulic

Hydraulic monitored safety valves 

PSV Pneumatic

Pneumatic monitored safety valves

Zero Pressure Monitor

Feedbacks the isolation status of a hazardous energy system

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Risks associated with hydraulic and pneumatic systems

The use of hydraulics and pneumatics is a reliable and highly precise method of moving loads. However, with all systems, there is a certain risk involved when this force holds a load during the transition between movements.

The most common causes of failures in pneumatic and hydraulic systems are:

  • Contamination caused by hydraulic fluid or internal wear
  • General wear and tear
  • Heat aging
  • Moisture and condensation
  • Poor lubrication

Safety circuits for light curtain

Valve control

Safety circuits for valve monitoring

Valve control

Safety circuits for valve monitoring

Safety circuits for interlock

Highest safety levels

To comply with category 4, ISO 13849-1 requires that the safety-related parts of the control system (SRP/CS) must be designed in such a way that a single fault in this system does not lead to a loss of the safety function.

Additionally, ISO 4413 and ISO 4414 describe in detail how functional safety is the preferred method to mitigate risks associated with hydraulic and pneumatic processes.

Fortress’s Fluidsentry offers secure electrically monitored safety valves for pneumatic and hydraulic systems, specially designed for use on Cat. 4, PLe, and SIL3 applications.

PROFIsafe and CIP safety

The Fortress Fluidsentry safety solution can communicate via the PROFIsafe and CIP safety protocols.

This compatibility allows for seamless integration of the system with existing network control systems that support these protocols, enabling safety information to be communicated quickly and accurately across the networks. This provides several benefits, including rapid detection of hazardous conditions and real-time responses to safety signals.

HSV hydraulische safety valve with electric monitoring

The Fluidsentry HSV system can be retrofitted into existing hydraulic systems to achieve the highest level of safety up to Cat. 4, SIL 3, PLe.

Fluidsentry HSV is an essential safety-related component of a hydraulic energy control system. Fortress’s monitored valve technology is designed as an interface between the operation of hydraulics and the electrical safety circuits of the machine.

  • Different variants available for CETOP 3, 5, 7, and 8 dimensions.
  • Redundant system through the use of two separate valves.
  • When the valve is energized in position, the forced safe contacts are switched.
  • When the electrical signal is interrupted, the supply is blocked and vented.
  • The safety device monitors the position of the valve in the de-energized state.

Different designs

Available in different CETOP sizes ranging from 40LPM to 550LPM.

Safe return hydraulic pressure

Fluidsentry HSV guarantees the safe flowback of hydraulic pressure to the tank by utilizing redundant measures to safeguard against a single point of failure.


Prevent danger

When the electrical signal is deactivated, the fluid supply is blocked and drained to prevent hazardous movements.

PSV Pneumatic safety valve with electrical monitoring

The Fluidsentry PSV system is a safety valve designed for machines powered by pneumatic energy or fluid power loads. The system can be retrofitted into existing pneumatic systems to achieve the highest level of safety up to Cat. 4, SIL 3, PLe.

The pneumatic safety valve is placed in series with the machine power supply. In order to allow the flow of pneumatic energy or fluid power, 24V is supplied to the Pneumatic Monitored Safety Valve (PSV). Once the Fortress PSV is deactivated, the downstream system is isolated and residual energy is dissipated.

  • The Fluidsentry PSV system is designed to shut off the energy supply and allow the escape of residual energy in the event of a malfunction or failure.
  • The PSV is equipped with pneumatic monitoring functionality to monitor the position of the valve during machine deactivation.
  • It features a dual, independent valve element configuration to provide redundant safety. Available in various valve sizes and can be configured for different pressure ranges.
  • Complies with various international standards and regulations, including the Machinery Directive 2006/42/EC and ISO 13849-1.
  • Suitable for use in a wide range of applications, including factories, production lines, and material handling systems.

Double NC-contacts

The PSV features double NC (Normally Closed) contacts that are directly operated by the valve element during the transition to the output state, and it is monitored in the deactivated state to ensure safety.

Position monitoring

The PSV incorporates a safety-rated device that monitors the position of the valve when it is in the deactivated state to ensure safe operation.

Mechanical bias

The valve is equipped with a mechanical bias that ensures the remaining fluid power is discharged when the valve is no longer powered.

ZPM zero pressure monitoring

The zero pressure monitoring, ZPM, provides feedback on the isolation status of a hazardous energy system through a single or dual channel. Dual channels are used to enhance reliability and prevent a single fault or malfunction from disabling the system.

The pressure monitoring system includes a two-pole positive-guided plunger-type switch with positive-opening contacts approved for safety category 4 applications. When the ZPM is used in conjunction with another safety function, a single pressure monitor is suitable for category 2 applications. Two independent units are suitable for pressure monitoring in category 3 or 4 applications.

The monitoring systems feature a non-adjustable setting between 3 and 6 psi for low-pressure switching and 15 psi for high-pressure switching. When the pressure drops below the set threshold, the monitoring system switches to indicate the isolation status of the hazardous energy system. This ensures that the pressure in the system is regulated and safety standards are maintained. 

Suitable up to Category 4

High-pressure operation up to 340 bar (34,000 kPa).

Detects complete isolation of hazardous fluid power in systems up to Category 4.

Aluminum or stainless steel

The Zero Pressure Monitor for pneumatic applications features an aluminum housing.

The Zero Pressure Monitor for hydraulic applications features a steel housing.

Integration possibilities

Zero pressure monitors are designed to be integrated into new or existing safety systems where residual pressure needs to be discharged.