Pin System Security Index, or PISS, is a security system that uses geometric features on the yoke to ensure that pneumatic connections between gas cylinders and machines using pressurized gas are not connected to the wrong gas of the yoke. This system can be seen on the anesthesia machine and portable oxygen administration set. It has no purpose other than a physical barrier to connect the wrong cylinder.
Video Pin Index Safety System
Drafts
The pin index security system uses the face seal between the cylinder valve and the corresponding yoke clip. There are two holes in the specific position on the cylinder valve body beneath the outlet port, in the position associated with the gas mixture, which prevents the cylinder connection to the yoke or pressure regulator with incorrect pin sets. The hole receives a pin of 4 mm diameter with a true 6 mm length aligned with the hole.
Maps Pin Index Safety System
Configure pin index
Each gas cylinder has a pin configuration to fit the respective gas yoke. See diagram for pin numbers; dimensions in millimeters.
- O 2 : 2.5
- N 2 O: 3.5
- Mixed O 2 and N 2 O (50%/50%), usually called Entonox: 7 (one pin, located in the middle)
- Air: 1-5
- Mixture of CO 2 and O 2 with more than 7% CO 2 : 1,6
- Mixture of CO 2 and O 2 with less than 7% CO 2 : 2,6
- Him: No pins
- Mixed O 2 and He with less than 80% He, commonly called Heliox: 2,4
- Mixed O 2 and He with more than 80% Dia: 4-6
- Cyclopropane: 3,6
- Ethylene: 1,3
- Nitrogen: 1-4
International Standard
- International Standard (ISO) and Europe (CEN)
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- EN ISO 407: Small medical gas tube - pin-index valve pin-type connection
The pin index system is a security system (PISS) designed to ensure that the correct gas is charged into the correct cylinder, and that the cylinder will only connect to the correct equipment. The hole position on the cylinder valve corresponds to the pin attached to the yoke attached to the equipment. The pin position for each medical gas is unique. If attempts are made to insert the wrong gas cylinder into a tight seal of yoke will not be made, because the pin can not be found.
The system requires a seal between the yoke and the valve to prevent leakage. This is called Bodok seal, and is a molded (or Neoprene) rubber washer supported by metal rims.
Security
It is possible to pass through the pin-index system if the pin is removed, damaged or rusted, if an additional wash is used, or on some valves with short faces above the holes, by flipping the gas cylinder. There is one report about the wrong colored cylinder that caused the error.
Alternate system
Large cylinders are more likely to be fitted with threaded connectors. One such system is the American CGA fittings. In Europe there are UK Standard (BS), German (DIN) and French (AFNOR) Standards, and Japan has Japanese Standard (JIS).
Blanking Plugs
Spark plug blanks (dummy cylinder heads) can be inserted into empty yokes to ensure that there is no leakage of the yoke when not in use.
References
Source of the article : Wikipedia
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