Licence: In copyright
Credit: Hygiene: a manual of personal and public health. Source: Wellcome Collection.
Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.
342/372 (page 330)
![the water has been boiled. At ordinary atmospheric pressure it is 100° C. (212° F.). The temperature of boihng is raised by subjecting the water to pressure. Consequently boiling water and the steam produced from it may be at any temperature. Thus steam may be {a) Under pressure, with a temperature above 212° F. (b) Not under pressure, at a temperature of 212° F. Steam when admitted into a disinfecting stove comes into contact with cold objects. // the steam is saturated, immediate condensation to t^Vtt P^rt of its original volume occurs. Its latent heat is at the same time evolved. The condensation causes enormous shrinkage in bulk. More steam is thus insucked into the partial vacuum produced, and this is repeated, until in every FiG. 57. Equifex Saturated Steam Disinfector. A—Disinfection chamber. B—Partition wall separating infected from dismfected side. 0—Door on disinfected side. D—Door on infected side. E E—Safety-locking bolt for securmg door. FF Stiffening rings on doors. G—Steam inlet from boiler. H—Steam separator for arrestmg water condensed in G. I—Valve controlling admission of steam to disinfecting chamber. K-Valve controlling admission of steam to coils. LM—Safety valves regulating steam pressure m chamber and coils respectively. NU—Pressure guages indicating steam pressure in chambers and coils respectively. OO—Objects after disinfection. P—Wheeled carriage and cradle for O J. Q—Hinged rails on which P runs. R-Exhaust pipe for steam and air on first admission. S—Thermometer showing rise of temperature (to control complete air evacuation). T—Valve for closing exhaust pipe R when air is completely evacuated. V—Sluice valve to cause sudden escape ot steam. W—Cock to admit steam to ejector. X—Exhaust pipe fitted with ejector for escape of steam before and of air during drying. Y—Valve for admission of air for drying under suction ot ejector, [in some types of this machine this valve is placed on the lower part of C] part of the mattress or other material undergoing disinfection equality of temperature is reached, when condensation of steam will cease, and disinfection is complete. // the steam is superheated and no condensation allowed, disinfection occurs by the relatively slow method occurring with dry heat. In practice at the early stage cooling causes some conversion of superheated into saturated steam, though subsequently the much slower process of disinfection](https://iiif.wellcomecollection.org/image/b21357675_0342.jp2/full/800%2C/0/default.jpg)
