Pin Index Safety System
The Pin Index Safety System, or PISS, is a safety system that uses geometric features on the yoke to ensure that pneumatic connections between a gas cylinder and a machine that uses pressurized gases are not connected to the wrong gas yoke. This system can be seen on an anesthesia machines and portable oxygen administration sets. It has no purpose other than a physical barrier to connecting the wrong cylinder.
Pin index configurations
Each gas cylinder has a pin configuration to fit its respective gas yoke. Refer to the diagram for pin numbers; dimensions are in millimeters.
- O2: 2,5[1][2]
- N2O: 3,5[1][2]
- Mixture of O2 and N2O (50% / 50%): 7 (a single pin, located in the centre)
- Air: 1-5[2]
- Mixtures of CO2 and O2 with more than 7% CO2: 1,6[1]
- Mixtures of CO2 and O2 with less than 7% CO2: 2,6[1]
- He: No pin
- Mixtures of O2 and He with less than 80% He, commonly called Heliox): 2,4[1]
- Mixtures of O2 and He with more than 80% He: 4-6[1]
- Cyclopropane: 3,6[1]
- Ethylene: 1,3[1]
- Nitrogen: 1-4
International Standards
- EN ISO 407 : Small medical gas cylinders - Pin-index yoke-type valve connections
The pin index system is a safety system (PISS) designed to ensure the correct gas is filled into the correct cylinder, and that the cylinder will only connect to the correct equipment. The positions of the holes on the cylinder valve correspond with the pins fitted to the yoke attached to the equipment. The pin positions for each medical gas are unique. If an attempt is made to fit the wrong gas cylinder to the yoke a tight seal will not be made, as the pins cannot locate.
The system requires a seal between the yoke and valve to prevent leakage. This is called a Bodok seal, and is a moulded rubber washer supported by a metal rim.Cite error: A <ref> tag is missing the closing </ref> (see the help page).
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- ^ a b c d e f g h Cite error: The named reference
pin codewas invoked but never defined (see the help page). - ^ a b c d Dosch, Michael P.; Tharp, Darin. "Supply system: Gases & electricity". The Anesthesia Gas Machine. University of Detroit. Retrieved 12 August 2017.
- ^ Srivastava, Uma (2013). "Anaesthesia gas supply: Gas cylinders". Indian Journal of Anaesthesia. 57 (5): 500–506. Retrieved 12 August 2017.