Trapped Key Interlock Switches

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Overview

CNC precision cut keys		Tested to 100,000 operations

Interlocking and Control Solutions

Trapped Key Interlocks—Why Use Them?

Based upon the premise that no one key can be in two places at once, key interlock systems can be configured to provide that a predetermined sequence of events takes place or that hazards have been reduced before operators can become exposed to them.

It is a mechanical system and is therefore widely used in applications including those where the location of plant, environment or explosive atmospheres make the use of electrical interlock systems unsuitable or expensive to install. In addition, unique coding can be provided, leading to a greater degree of security and tamper-resistance.

Why Prosafe?

In order to derive the full benefits from a trapped key interlocking system its components must be totally practical, easily maintainable and readily available. Prosafe's unique key and code barrel gives the ability for even complicated interlocking systems and spare parts to be ordered from our worldwide network of distributors—fast! A first for trapped key interlocks.

Five Unique Prosafe Benefits

Compare the following to other trapped key manufacturers:

1.	All stainless interlocking and coded parts—including the code barrel and internal components at no extra cost.
2.	Weather cap as standard—no extra charge for dust caps and seals.
3.	Standard red color-coded key and ID tags—at no extra charge.
4.	Custom color/text keys and ID tags—nominal extra charge.
5.	A complete range of isolators, key exchange, miniature valve interlocks and gate interlocks—all using the same key principle.

CE Marking—Tested and Approved

Only Prosafe products carry the prestigious BG mark. A sign of safety, independently tested by the German Berufsgenossen-schaftliches Institut für Arbeitssicherheit, "BIA." Additional tests for valve interlocks include Lloyds Certificate for fire test and salt-mist resistance.

Over 100,000 Operations

Prosafe products have been subjected to independent, exhaustive testing. With only a small amount of lubricant added infrequently, keys were inserted, rotated and removed at a rate of 12 times per minute. After 100,000 operations (at 10 operations a day this is equivalent to 27 years) the unit was functioning satisfactorily and most importantly would "pass" only the original or equivalent new key. No incorrect keys could operate the lock, underlining the unit's integrity as well as longevity.

The Prosafe Advantage

Stainless steel construction.

The Advantage

90° Key Operation





Prosafe Keys

Compact, solid and sturdy keys supplied with dust seals and coded tagging. Optional colors/text are available.

Design Suggestions for an Interlocking System

Plant and Machinery Interlocking



The Prosafe Advantage

Stainless steel construction.

Illustrated Principles of Trapped Key Interlocking



Sequence of Operation

1.	The ETU isolator has two keys. One is a nonremovable key. The other key (a "AA" coded key) can be removed after a timed duration, which is set by a potentiometer inside the ETU isolator. Turn the nonremovable key to turn the hazardous machine motion off and start the timer. When the time expires, the Key Free LED turns ON. Remove the "AA" key.
2.	Insert the "AA" key into the Key Exchange Unit (KEX) and turn it 90°.
3.	Turn one of the "AB" keys 90° and remove it from the KEX. This traps the "AA" key in the KEX and prevents the restarting of the machine.
4.	Insert the "AB" key into the Single-key Bolt Lock (SBL) and turn it 90° to gain partial body access to the machine.

5.	Turn the second "AB" key 90° and remove it from the KEX. Removal of this key also traps the "A" key in the KEX and prevents the restarting of the machine.
6.	Insert the "AB" key into the Dual-key Access Lock (DAL) and turn it 90°.
7.	Turn the "AC" key 90° and remove the "C" key. Rotate the access handle to allow full body entry into the hazard zone.
8.	Take the "AC" key into the hazard zone, insert it into the rotary key switch (RKSE) and turn it 90° to send a signal to the machine control system, to allow the machine to operate in a slow or teach mode.
9.	Reverse the process to return the machine to full operational mode.

Bill of Materials

Item	Quantity	Description	Cat. No.
1	1	Single Key Time Delayed with an AA Primary Key	440T-MSTUE11AA
2	1	Key Exchange Unit, AB Primary Key, Two B Secondary Keys Trapped (included)	440T-MKEXE11AAABAB
3	1	Single Bolt Lock, AB Primary Key	440T-MSBLE10AB
4	1	Dual Access Lock, AB Primary Key, C Secondary Key Trapped (included)	440T-MDALE10ABAC
5	1	Rotary Key Switch, AC Primary Code Barrel	440T-MRKSE10AC
6	1	AA Key	440T-AKEYE10AA
Note: Primary keys must be ordered separately, when not provided for by a previous sequential trapped key. In the example above, only one primary key must be ordered separately. The remaining primary keys are provided by a previous sequential secondary (trapped) key.

Code Selection

Ordering Prosafe trapped key products requires codes to be included in the catalog number.

• The codes are added to the end of the catalog number.
  
• Each code must be two characters in length.
  
• The first code(s) is the primary code and the last code(s), if necessary, are the secondary code(s).
  
• Primary codes do not include the key. The key must be ordered separately or must come from a previous operation.
  
• Secondary codes come complete with a key, as the key is trapped in the code barrel.
  
• Use the tables on Key Coding to select and track codes.
  

Ordering Example 1



Order catalog number 440TMDALE100AAAB to get a Dual key Access Lock with an "AA" primary code and a "AB" secondary code, with a "AB" key included.

Ordering Example 2



Order catalog number 440TMKEXE16AAABACACAC to get a key exchange unit with "AA" and "AB" primary codes and three "AC" secondary codes. The "AA" and "AB" keys are not included. The three "AC" keys, which are trapped in the secondary code barrels, are included.

The Prosafe Advantage

Stainless steel construction.

Key Coding

Below is an example reference guide that is useful in selecting and tracking codes. Start down the Aa column as the lower codes (typically Aa to Za) are stocked. The chart continues on to Zz. Note that there are only 25 letters used—Q is not used. Codes are ordered with upper case letters. Labels with two letter codes will show the first letter in the upper case and the second letter in lower case.