Ds = k(ts + tc + tr ) + dpf – Honeywell FF-SNC User Manual

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Safety Products for Machine Safeguarding -

© 2002 - 2004 Honeywell International Inc. All rights reserved.

Safety Distance Calculations per EN 294 European standard

The dimensions of openings correspond to the narrowest dimension of a slot opening (for openings greater than 120 mm / 4.72 in, refer to the
EN 294 standard).
Safety distances

sr for regular openings for persons of 14 years of age and above:

Part of body

Illustration

Opening size

Safety distance

sr

Slot

Fingertip

e

4

2

4 < e

6

10

Finger up to knuckle joint

6 < e

8

20

8 < e

10

80

Or

10 < e

12

100

12 < e

20

120

hand

20 < e

30

850*

Arm up to junction with shoulder

30 < e

40

850

40 < e

120

850

Safety Distance Calculations per US ANSI / OSHA standard

Ds = K(Ts + Tc + Tr ) + Dpf

With:

Ds = minimum safe distance between safeguarding device and hazard
K =

speed constant: 1,6 m/sec (63 in/sec) minimum based on the movement being the hand/arm only and the body being stationary (a greater
value may be required in specific applications and when body motion must also be considered)

Ts = worst stopping time of the machine/equipment
Tc = worst stopping time of the control system
Tr = response time of the safeguarding device including its interface (Tr for interlocked barrier may include a delay due to actuation. This delay

may result in Tr being a deduct– negative value).

Dpf = the “Depth penetration factor” is the maximum travel towards the hazard if the guard can be opened a certain width or amount before a

stop is signaled.

Dpf values from OSHA O-10 Table:

If the maximum width or diameter

Dpf equals (mm/in)

of the opening is less

than or equal to (mm/in)

6,4 / 0.25

12,7 / 0.5

9,5 / 0.375

38,1 / 1.5

12,7 / 0.5

63,5 / 2.5

15,9 / 0.625

88,9 / 3.5

19,1 / 0.75

139,7 / 5.5

22,2 / 0.875

165,1 / 6.5

31,8 / 1.25

190,5 / 7.5

38,1 / 1.5

317,5 / 12.5

47,6 / 1.875

393,7 / 15.5

54 / 2.125

444,5 / 17.5

Note: Over 54 mm / 2.125 in, the Dpf equals 800 mm / 31.5 in,

with a maximum allowable opening of 152,4 mm / 6 in.

Example: Dpf = 0 when the guard can be opened up to, but less than 6,4 mm / 0.25 in before issuing a stop command.
Dpf = 444,5 mm / 17.5 in if the guard can be opened 54,0 mm / 2.125 in.
At no time can the opening be greater than 152,4 mm / 6 in before issuing a stop command.

For more information, refer to the US regulations and standards (OSHA 29 CFR 1910.212 & 1910.217, ANSI B11.19 and ANSI/RIA R15.06).

*

If the length of the slot opening is

≤≤≤≤≤

65 mm / 2.56 in, the thumb will act as a stop and the safety distance can be reduced to 200 mm / 7.88 in).

For more information on the guards installation, refer to the European standards: EN 811, EN 953, EN 294

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