|Object Type:||Stationery/Office Items|
|Object Name:||Slide Rule for Control Valve Sizing|
|Year of Manufacture:||1967|
|Location:||Archive Object Store|
Fisher Control Valve Sizing Rule Mark VII
In the 1950s and 1960s the Fisher Governor Company (now Fisher Controls International LLC a part of the Emerson Process Management Division of Emerson) developed specialist slide rules to aid in the selection of Control Valves for either liquid, steam or gas service.
This Fisher Control Valve Sizing Rule Mark VII was made by Blundell Harling (P2734) for GEC-Elliott Control Valves Ltd, Rochester, England, ©1967. This duplex plastic rule has 17 specialist scales for gases, steam and liquids from which the size parameters Cv, Cg or Cs can be determined given pressure drop, inlet pressure and flow rate, specific gravity (liquid) or inlet density (gas/vapour), temperature and degree of superheat (steam).
This imperial rule has a fabric backed PVC slip case. Several versions of the Fisher rule were made including one by Pickett for the American Fisher company.