Short pump barrel, long plunger and sand settling structure are used to prevent sand particles from entering the pump barrel, reduce sand sticking and prevent sand burial.
Pumps are typically used in sandy applications and offer the following advantages:
• The motion of traveling barrel keeps the fluid moving and the sand is almost flushed out until the pump seat collars. Minimizes the potential for sand to settle around the pump and get stuck in the tubing.
• The traveling-barrel pump is especially suitable for intermittent pumping of oil wells. Since the moving valve at the top of the pump is closed when the well is closed, sand cannot settle inside the pump. This prevents sand from settling inside the pump, a condition that could cause the plunger to stick, or prevent the fixed valve from opening when the well resumes pumping.
• The traveling and standing valves on the pump have open cages, which are more rigid and provide more fluid passage than closed cages.
• External and internal balanced pressures on the moving or stationary barrel provide bottom-anchored pumps with greater burst resistance than top-anchored pumps.

Traveling-barrel, bottom-anchor pumps have the following limitations:
• In wells with low static liquid levels, traveling barrel pumps are at a disadvantage. To enter the pump chamber, the fluid must rise through the pull tube and plunger, then through the stationary valve.
• The fixed valve is located at the top of the plunger and has a smaller diameter than the moving valve, thus providing more fluid resistance than the larger fixed valve of a fixed barrel pump. This promotes gas leakage and may cause gas disturbances in the pump.
• Long traveling barrel pumps should not be run in deep wells. When the fixed valve (located in the plunger top retainer) is closed, the hydrostatic column load is transferred by the plunger through the pull tube and pressed into the pump seat coupling. In deep wells, this load will be sufficient to place a bow in a long draw tube, creating resistance between the pull plug and the draw tube.
• Traveling-barrel pumps do not normally operate in wells with slanted bores or offsets at the pump base coupling. Either condition can cause excessive wear on the pump barrel, which reduces the pump stroke and therefore displacement.