Palestra Dietrich warmbier

ISSA Seminar – Functional Safety and Validation
Fluid power safety trainingFluid power safety trainingFluid power safety trainingFluid power safety training
Dietrich Warmbier - Ross Controls
Global Safety Product Manager
dietrich.warmbier@rosscontrols.com
+49 171 5800342

ISO 14118ISO 14118ISO 14118ISO 14118

Pneumatic Lockout
ISO 14118 (former EN 1037)
Safety of machinery - Prevention of unexpected start-up
OSHA 1910.147 The control of Hazardous energy
ANSI Z244 Lockout/Tagout
• Lockout whenever a body part is put into a point of
operation

Pneumatic Lockout
• Requirements (DIN EN 1037)
• A manually operated valve
• Not be used for any other function
• Located outside of
hazardous areas
• Should only be able
to be locked in off position
• Easily identified and operated
• Tamper resistant

Pneumatic Lockout
Best Practice (ANSI B11.0 & B155.1)
“Positive action” which would indicate only two positions (ON and OFF)
A method for the employee to verify that the energy has dissipated after
Full diameter exhaust (rapid release of stored energy)
Example: 230l at 7 bar (valve G ½”)
• L-O-X® - Valve = 35 seconds
• Bleed port > 11 minutes

Pneumatic Lockout
„Napo in … Safe maintenance!“ is presented by courtesy of
Via Storia, France

Pneumatic Lockout
„Napo in … Safe maintenance!“ Episode „Lock out“
https://www.youtube.com/watch?v=G2ERlrWAmAE

Process controlProcess controlProcess controlProcess control
The Control system doesdoesdoesdoes NOT ENDNOT ENDNOT ENDNOT END with the wire!with the wire!with the wire!with the wire!
It includes all components involved in performing the safety function; sensors, manual input, and
mode selection elements, interlocking and decision-making circuitry, and output elements that
control machine operating devices or mechanisms.
Input devices
Light curtains
Palm buttons
Etc..
Control
System
Logic
Mechanical
Control Devices
Air & Hydraulic
Valves
Mechanical
latches
Etc..

Process controlProcess controlProcess controlProcess control

80 psi
0 psi
Hazards & FailuresHazards & FailuresHazards & FailuresHazards & Failures

80 psi
80 psi

80 psi
??? psi
Outlet Pressure is a function of:
• Downstream volume
• Inlet Pressure
• Exhaust area
• Inlet area

Why use a control reliable valve?Why use a control reliable valve?Why use a control reliable valve?Why use a control reliable valve?

PNEUMATIC 3/2- and 5/2-SAFETY VALVE:
BASICALLY A PNEUMATIC SAFETY RELAY!
Intended for applications
Valve can be main air supply and
exhaust valve for whole machine or a zone
Valve can be used for safety control of
power units
Many systems utilize a downstream
pressure switch to verify that pressure is
exhausted if the volume and risk assessment warrants it
Safety Process controlSafety Process controlSafety Process controlSafety Process control

• Pneumatic safety reduction measures
– Safe exhaust
– Return cylinder to safe position
– Trap pressure as required
Pneumatic safetyPneumatic safetyPneumatic safetyPneumatic safety

Transfer press line part removal
Operator removes part from conveyor A
Part is placed on rack C
Fork trucks remove full racks, load empty racks
ExampleExampleExampleExample –––– Safety Exhaust FunctionSafety Exhaust FunctionSafety Exhaust FunctionSafety Exhaust Function

Hazardous situation
Once rack C is full table D must rotate
Operator controls 3/2 NC valve at control panel B
Rotation creates crushing/shearing hazard
Crushing/Shearing
Hazard

Safety controls
Electrical push button controls 3/2 NC valve
Valve supplies air motor controlling rotation
Light Curtain E ensures no exposure to crush point
Motionless
2
3 1
Rotating
2
3 1

PL c
• Light curtain cycle rate = every 1 minute
• Valve cycle rate = every 15 minutes
Light Curtain Valve
cycle time (sec) 60 900
hours per day 8 8
days per week 5 5
weeks per year 52 52
cycles per year 124800 8320
Input Logic Output
Description Safety Mat Safety Relay Valve
B10D 20000000
nop 124800 8320
MTTFD 100 100 100
DC 99% 99% 0%
Category 4 4 1
System MTTFD 33 High
System DC 66% Low
System Category 1
PL c

Valve failure mode – Stuck in shifted position
Rotation continued
Light Curtain & relay had no effect
Rotating
2
3 1

Pneumatic solution
Redundant, internal/ external-monitoring double-valve
Fail safe (exhaust)
Removes supply when de-energized (stops rotation)
2
3 1

Safety light curtain cycle rate = every 1 minute
Valve cycle rate = every 15 minutes
PL e
Light Curtain Valve
hours per day 8 8
days per week 5 5
Input Logic Output
Description Light curtain Safety Relay Valve
B10D 20000000
nop 124800 8320
MTTFD 100 100 2500
DC 99% 99% 99%
Category 4 4 4
System DC 99% High
System Category 4
PL e

3/2-safety valve solutions
Internally monitored Externally monitored
with soft-start w/o soft-startw/o
soft-start

Installation Internal Monitored valve
Safety Relay
Example only, no verified circuit

Installation External Monitored valve
Example only, no verified circuit

• Pneumatic safety reduction measures
– Safe exhaust
– Return cylinder to safe position
– Trap pressure as required
Pneumatic Safety

Pneum. und hydropneum. cylinderpress
Example - Vertical Cylinder

5/2 Spring return valve
Dangerous failures
◦ Fails to return, continue extending
◦ Sluggish valve increases stopping time
◦ Leakage allows residual pressure buildup
◦ Requires supply pressure to return
Cylinder return

Example - Vertical Cylinder – Safe return
Single channel example
2
4
3
5
1
Safety Relay

2
4
3
5
1
Safety Relay
Single channel failure example

2
4
3
5
1
pinched
Safety Relay
Single channel failure example

Two hand control system = 1 min cycle rate
PL c
Cycles Two Hand Valve
hours per day 8 8
days per week 5 5
Input Logic Output
Description Two Hand Safety Relay Valve
B10D 1000000 20000000
nop 120000 120000
MTTFD 83 100 100
DC 99% 99% 0%
Category 4 4 1
System DC 68% Low
System Category 1
PL c

Cylinder Stop FunctionCylinder Stop FunctionCylinder Stop FunctionCylinder Stop Function
• Trap pressure to maintain position
– Prevent hazards due to gravity
– Risk = failure of control valve
2
4
3
5
1 1

PL c
If air piloted it requires the proper
function of the control valve and po
check.
PO Check is mechanically based
with increased off force.
Control valve overrides po check.
cycle time (sec) 60
hours per day 24
days per week 7
weeks per year 52
cycles per year 524160
Input Logic Output Output
Description AOPD Safety PLC Valve PO Check
B10D 20000000 20000000
nop 524160 524160
MTTFD 82 2500 100 100
DC 99% 99% 0% 0%
Category 4 4 1 1
System DC 38% None
System Category 1
PL c

– Addition of safety exhaust
• Category 4 exhaust
• Category 1 load holding
2
4
3
5
2
3
1 1

Load Holding cycle time (sec) 60
hours per day 24
days per week 7
weeks per year 52
B10D 20000000 20000000
nop 524160 524160
MTTFD 82 150 382 100
DC 99% 99% 99% 0%
Category 4 4 4 1
System DC 68% Low
System Category 1
PL c
Safety Exhaust cycle time (sec) 60
hours per day 24
days per week 7
weeks per year 52
Input Logic Output
Description AOPD Safety PLC Valve
B10D 20000000
nop 524160
MTTFD 82 150 382
DC 99% 99% 99%
Category 4 4 4
System DC 99% High
System Category 4
PL e
PL cPL e

Category 2 pilot operated check valves
Force guided positively driven switch
Signal can be pneumatic and/or electric

– Addition of safety exhaust & PO Check monitoring
• Cat 4 safety exhaust
• Cat 2 load holding
2
4
3
5
2
3
1 1

hours per day 24
days per week 7
weeks per year 52
Input Logic Output
B10D 20000000
nop 524160
MTTFD 82 150 382
DC 99% 99% 99%
Category 4 4 4
System DC 99% High
System Category 4
PL e
PL cPL e

– Solenoid piloted PO Check with monitoring
• Only cycles when the main air exhaust cycles
• Can improve the overall MTTFD
• May not improve PL
2
4
3
5
2
3
1 1

• Category 4 exhaust
• Category 3 load holding
2
4
3
5
2
3
1 1

Load Holding cycle time (sec) 60
hours per day 24
days per week 7
weeks per year 52
B10D 20000000 20000000
nop 524160 524160
MTTFD 82 150 382 38
DC 99% 99% 99% 90%
Category 4 4 4 3
System MTTFD 21 Medium
System DC 94% Medium
System Category 3
PL d
hours per day 24
days per week 7
weeks per year 52
Input Logic Output
B10D 20000000
nop 524160
MTTFD 82 150 382
DC 99% 99% 99%
Category 4 4 4
System DC 99% High
System Category 4
PL e
PL dPL e

Old Solution – CAT 1 Recent Solution – CAT 3
New Solution – CAT 4

ROSS – Your Partner for Pneumatic Safety Solutions

Dietrich Warmbier
Global Safety Product Manager
Contact data:
Dietrich Warmbier
Ringbergstr. 36
D-67744 Schweinschied
- Germany -
Tel.: +49 (0)6753/123965
Fax: +49 (0)6753/123966
Mobile: +49 (0)171/5800342
E-Mail: dietrich.warmbier@rosseuropa.de

Palestra Dietrich warmbier

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