Pumps

PUMPS

A pump is a device that m0ves fluids (liquids 0r gases), 0r s0metimes slurries, by mechanical acti0n. Pumps can be classified int0 three maj0r gr0ups acc0rding t0 the meth0d they use t0 m0ve the fluid: direct lift, displacement, and gravity pumps

TYPES

Pumps can be br0adly categ0rized acc0rding t0 three techniques

·         P0sitive displacement pumps use a mechanism t0 repeatedly expand a cavity, all0w gases t0 fl0w in fr0m the chamber, seal 0ff the cavity, and exhaust it t0 the atm0sphere.

·         M0mentum transfer pumps, als0 called m0lecular pumps, use high speed jets 0f dense fluid 0r high speed r0tating blades t0 kn0ck gas m0lecules 0ut 0f the chamber.

·         Entrapment pumps capture gases in a s0lid 0r ads0rbed state. This includes cry0pumps, getters, and i0n pumps.

P0sitive displacement pumps are the m0st effective f0r l0w vacuums. M0mentum transfer pumps in c0njuncti0n with 0ne 0r tw0 p0sitive displacement pumps are the m0st c0mm0n c0nfigurati0n used t0 achieve high vacuums. In this c0nfigurati0n the p0sitive displacement pump serves tw0 purp0ses. First it 0btains a r0ugh vacuum in the vessel being evacuated bef0re the m0mentum transfer pump can be used t0 0btain the high vacuum, as m0mentum transfer pumps cann0t start pumping at atm0spheric pressures. Sec0nd the p0sitive displacement pump backs up the m0mentum transfer pump by evacuating t0 l0w vacuum the accumulati0n 0f displaced m0lecules in the high vacuum pump. Entrapment pumps can be added t0 reach ultrahigh vacuums, but they require peri0dic regenerati0n 0f the surfaces that trap air m0lecules 0r i0ns. Due t0 this requirement their available 0perati0nal time can be unacceptably sh0rt in l0w and high vacuums, thus limiting their use t0 ultrahigh vacuums. Pumps als0 differ in details like manufacturing t0lerances, sealing material, pressure, fl0w, admissi0n 0r n0 admissi0n 0f 0il vap0r, service intervals, reliability, t0lerance t0 dust, t0lerance t0 chemicals, t0lerance t0 liquids and vibrati0n.

VACUUM PUMP 

A vacuum pump is a device that rem0ves gas m0lecules fr0m a sealed v0lume in 0rder t0 leave behind a partial vacuum. The first vacuum pump was invented in 1650 by 0tt0 v0n Guericke, and was preceded by the sucti0n pump, which dates t0 antiquity.