An air vessel is fitted to reciprocating pumps to provide continuous and uniform fluid flow. It contains compressed air above liquid and has an opening where liquid can flow in and out. This allows the pump to run at high speeds without separation. The document also describes equations to calculate head loss due to friction in suction and delivery pipes at different points in the stroke, as well as equations for pressure head in the cylinder.

1. RECIPROCATING PUMP WITH AIR VESSEL

3. AIR VESSEL
• An air vessel is a closed chamber containing compressed air in the top
portion and liquid in the bottom of the chamber.
• At the base of the vessel there is a opening where the liquid can flow
in and out of the vessel.
• Air vessel is fitted for the following reasons
(a) To obtain continuous supply of fluid at a uniform rate
(b) To save a considerable amount of work in overcoming the
frictional resistance in the suction and delivery pipe.
(c) To run the pump at a high speed without separation

10. EFFECT OF ACCELERATION AND FRICTION IN
SUCTION AND DELIVERY PIPES DUE TO FRICTION
• The loss of head due to friction at the beginning of the suction stroke
and delivery stroke (i.e) θ = 00
hfs = 0
• The loss of head due to friction at the middle of the suction and
delivery stroke (i.e) θ = 900
hfs =
4𝑓𝑙 𝑠
2𝑔𝑑 𝑠
(
𝐴𝜔𝑟
𝑎 𝑠
)2
• The loss of head due to friction at the end of the suction and delivery
stroke (i.e) θ = 1800
hfs = 0

11. PRESSURE HEAD IN THE CYLINDER
• Pressure head in the cylinder at the beginning of the suction stroke
= 10.3-(hs+has)
• Pressure head in the cylinder at the middle of the suction stroke
= 10.3-(hs+hfs)
• Pressure head in the cylinder at the end of the suction stroke
= 10.3-(hs-has)
• Pressure head in the cylinder at the beginning of the delivery stroke
= 10.3+(hd+had)
• Pressure head in the cylinder at the middle of the delivery stroke
= 10.3+(hd+hfd)
• Pressure head in the cylinder at the end of the delivery stroke
= 10.3+(hd-had)