There are two choices of pump type for wellhead control panel hydraulic power unit, air driven and motor driven. Some of project use air driven pump, some of it use motor driven pump, and some of it also use both of them (usually air driven pump are used for High Pressure header and motor driven pump are used for Medium Pressure header). So what it should be? Air driven or motor driven hydraulic pump?
The selection of using air driven or motor driven hydraulic pump depends on the following issue:
The available utilities. Do the instrument air or instrument gas available? If not available, then the choice is only to use motor driven pump.
The safety concern. Air driven pump using no electric power at all, while motor driven pump use electric power. This becomes a concern because around the wellhead control panel (if not located on a very far remote deck or area) is an area with possibility to have a flammable fluid present. Thus, most of the hydraulic pump for wellhead control panel is using air driven pump rather than motor driven.
The compactness of the wellhead control panel. This becomes a concern when the space is very expensive to extend just to accommodate big wellhead control panel. Normally, the air driven pump is more compact, lightweight, and easy to install or operate rather than motor driven pump.
Speed of charge. The accumulator of the hydraulic power unit is always having certain charging time requirement. Faster the charging time required bigger the pump flow rate needed. In general, the capacity of the motor driven hydraulic pump is bigger than the air driven pump. Thus if the charging time is very critical to achieved, then motor driven pump can be a good choices.
The above issues is just several things that must be take into consideration to chose the pump driver type. But as default pump type, the air driven hydraulic pump should be selected except the speed of charge isn’t sufficient or the utilities isn’t available then the motor driven pump should be selected.