Safety In Application; Building In Safety - Danfoss PVG 120 Technical Information

Technical Information

Safety in Application

Building in safety

PVG 120 Proportional Valve Group
All makes and all types of control valves (incl. proportional valves) can fail. Thus the necessary protection
against the serious consequences of function failure should always be built into the system. For each
application should be made an assessment for the consequences of pressure failure and uncontrolled or
blocked movements.
To determine the degree of protection that is required to be built into the application, system tools such
an FMEA (Failure Mode and Effect Analysis) and Hazard and Risk Analysis can be used.
IEC FMEA – EN 61508.
FMEA is a tool used for analyzing potential risks. This analytical technique is utilized to define, identify,
and prioritize the elimination or reduction of known and/or potential failures from a given system before
it is released for production. Please refer to IEC FMEA Standard EN 61508.
Hazard and Risk Analysis – ISO 12100-1/14121.
This analysis is a tool used in new applications as it will indicate whether there are special safety
considerations to be meet according to the machine directives EN 13849. Dependent on the determined
levels conformety this analysis will detirmine if any extra requirements for the product design,
development process, production process or maintenance, i.e. the complete product life cycle.
W
Warning
All makes/brands and types of directional control valves inclusive proportional valves can fail and
cause serious damage. It is therefore important to analyze all aspects of the application. Because the
proportional valves are used in many different operation conditions and applications, the manufacturer
of the application is alone responsible for making the final selection of the products – and assuring that
all performance, safety and warning requirements of the application are met. The process of choosing the
control system and safety levels is governed by the machine directives EN 13849 (Safety related
requirements for control systems).
PVG 32 – mainly used in system with fixed displacement pumps.
•
PVSK, commonly used in crane application - full flow dump
•
PVPX, LS dump to tank
PVG 100 – Alternative LS dump or pilot supply disconnect.
•
PVPP, pilot oil supply shut off
•
External cartridge valve connecting LS Pressure to Tank
•
External cartridge valve connecting main Pressure to Tank
PVG 120 – Pump disconnect / block for variable pumps.
•
PVPE, full flow dump for the PVG 120.
520L0356 • Rev JA • Mar 2014 11