Bodok seal
Encyclopedia
The Bodok seal is a specialised washer that ensures a gas-tight seal between the cylinder yoke or regulator of an anaesthetic machine
or any medical device requiring a gas supply, and a gas cylinder
. It was introduced along with the pin index safety system
during the 1950s.
Attachment and detachment of a gas cylinder leads to constant wear and tear, due in part to mechanical distress and to gaseous compression and expansion. (Adiabatic
effects in rapidly expanding compressed gases can generate very high temperatures, up to 1000 degrees Celsius.) Prior to the introduction of the Bodok seal, the traditional fibre washer would frequently splay and cause leakage or adhere to the regulator, thus requiring the use of pliers and considerable force to remove it.
The Bodok seal consists of a neoprene
washer with a peripheral metal reinforcing ring which prevents splaying of the washer. The seal is incombustible and resistant to the high pressures imposed upon it by cylinder gases (a full cylinder has a pressure of approx 2000 psi / 140 bar).
Care must be taken when replacing gas cylinders that the bodok seal does not stick to the cylinder face when the cylinder is replaced and is thus 'lost' when the new cylinder is fitted and is therefore impossible to achieve a gas tight seal.
Bodok seals are also used in emergency oxygen kits used in scuba diving, but diving regulators used underwater generally use a conventional o-ring seal.
Cost: About £0.60 (UK) each.
Anaesthetic machine
The anaesthetic machine is used by anaesthesiologists and nurse anaesthetists to support the administration of anaesthesia...
or any medical device requiring a gas supply, and a gas cylinder
Gas cylinder
A gas cylinder is a pressure vessel used to store gases at above atmospheric pressure. High pressure gas cylinders are also called bottles. Although they are sometimes colloquially called "tanks", this is technically incorrect, as a tank is a vessel used to store liquids at ambient pressure and...
. It was introduced along with the pin index safety system
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 machine.Each gas...
during the 1950s.
Attachment and detachment of a gas cylinder leads to constant wear and tear, due in part to mechanical distress and to gaseous compression and expansion. (Adiabatic
Adiabatic process
In thermodynamics, an adiabatic process or an isocaloric process is a thermodynamic process in which the net heat transfer to or from the working fluid is zero. Such a process can occur if the container of the system has thermally-insulated walls or the process happens in an extremely short time,...
effects in rapidly expanding compressed gases can generate very high temperatures, up to 1000 degrees Celsius.) Prior to the introduction of the Bodok seal, the traditional fibre washer would frequently splay and cause leakage or adhere to the regulator, thus requiring the use of pliers and considerable force to remove it.
The Bodok seal consists of a neoprene
Neoprene
Neoprene or polychloroprene is a family of synthetic rubbers that are produced by polymerization of chloroprene. Neoprene in general has good chemical stability, and maintains flexibility over a wide temperature range...
washer with a peripheral metal reinforcing ring which prevents splaying of the washer. The seal is incombustible and resistant to the high pressures imposed upon it by cylinder gases (a full cylinder has a pressure of approx 2000 psi / 140 bar).
Care must be taken when replacing gas cylinders that the bodok seal does not stick to the cylinder face when the cylinder is replaced and is thus 'lost' when the new cylinder is fitted and is therefore impossible to achieve a gas tight seal.
Bodok seals are also used in emergency oxygen kits used in scuba diving, but diving regulators used underwater generally use a conventional o-ring seal.
Cost: About £0.60 (UK) each.
External links
- Bodok seal note (See "Historical Forum" following "Nerve Plexus" article)