A pump comprises a housing (141) having a cavity (142) with an inlet valve (143), an apparatus (144) for raising fluid pressure in the cavity (142) and a discharge valve (145), the discharge valve (145) comprises a valve head (160) movable between an open and closed position and a valve seat (167), wherein the pump further comprises a booster piston (182) arranged in a booster cylinder (183), the booster piston (182) has a first face (191) exposed to a low pressure zone (189) and a second face (194) exposed to fluid pressure in the cavity (142), and at least one of the booster piston (182) and the booster cylinder (183) is movable relative to the other to add an opening force to the discharge valve. The pump is preferably a mud pump for circulating drilling mud through a drill string in a wellbore or a cement pump which may be of the type for pumping cement into a wellbore. Also disclosed is a method for facilitating opening a valve comprising a valve head (160) and a valve seat (167), the valve head (160) is movable a predetermined distance from a closed position on the valve seat (167) to a fully open position distant on the valve seat, and the method comprises the step of adding a force to the valve head (160) along a small portion of the predetermined distance.

Described is a multi-stage pump having at least two stages. The multi-stage pump includes a first pump stage and a second pump stage each having a chamber of different diameter and volume. The multi-stage pump also includes a plunger having first and second plunger sections. The first plunger section has a first plunger diameter, a first end configured for coupling to a drive mechanism, and a second end opposite to the first end. The second plunger section has a second plunger diameter that is less than the first plunger diameter, a third end in contact with the second end of the first plunger, and a fourth end opposite the third end. Movement of the plunger produces a displacement volume for the first chamber that is different than a displacement volume produced for the second chamber. The multi-stage pump can be configured in different operational modes to provide different flow rates.

A high-viscosity fluid pumping system includes a reservoir defining an interior for holding a fluid and a pump assembly having an inlet and an outlet. The pump assembly includes a housing defining a chamber, a check valve and a piston. The inlet provides fluid communication between the interior of the reservoir and the chamber. The chamber is in fluid communication with the outlet. The check valve is positioned between and fluidly connected to the outlet and the chamber and permits the fluid to move from the chamber to the outlet. The piston is positioned in the chamber and moves from a retracted position, in which the chamber is in fluid communication with the inlet, and an extended position to move the fluid through the check valve to the outlet. At least one heater is provided to heat the fluid in at least one of the pump assembly and the reservoir.

A pump comprises a housing (141) having a cavity (142) with an inlet valve (143), an apparatus (144) for raising fluid pressure in the cavity (142) and a discharge valve (145), the discharge valve (145) comprises a valve head (160) movable between an open and closed position and a valve seat (167), wherein the pump further comprises a booster piston (182) arranged in a booster cylinder (183), the booster piston (182) has a first face (191) exposed to a low pressure zone (189) and a second face (194) exposed to fluid pressure in the cavity (142), and at least one of the booster piston (182) and the booster cylinder (183) is movable relative to the other to add an opening force to the discharge valve. The pump is preferably a mud pump for circulating drilling mud through a drill string in a wellbore or a cement pump which may be of the type for pumping cement into a wellbore. Also disclosed is a method for facilitating opening a valve comprising a valve head (160) and a valve seat (167), the valve head (160) is movable a predetermined distance from a closed position on the valve seat (167) to a fully open position distant on the valve seat, and the method comprises the step of adding a force to the valve head (160) along a small portion of the predetermined distance.

Described is a multi-stage pump having at least two stages. The multi-stage pump includes a first pump stage and a second pump stage each having a chamber of different diameter and volume. The multi-stage pump also includes a plunger having first and second plunger sections. The first plunger section has a first plunger diameter, a first end configured for coupling to a drive mechanism, and a second end opposite to the first end. The second plunger section has a second plunger diameter that is less than the first plunger diameter, a third end in contact with the second end of the first plunger, and a fourth end opposite the third end. Movement of the plunger produces a displacement volume for the first chamber that is different than a displacement volume produced for the second chamber. The multi-stage pump can be configured in different operational modes to provide different flow rates.

A pump for use with a material sprayer includes a cylinder, a piston, a pump head, first and second check valves, and an elbow connected to the cylinder. The cylinder and the piston are coaxial with a pump axis. The pump head is configured to make a mechanical connection with the reciprocating drive mechanism so as to allow the reciprocating drive mechanism to reciprocate the piston along the pump axis. The elbow includes a first end, a second end, and an inner fluid channel. The first end is configured to make a fluid connection with the hopper. The second end is configured to be fixed with respect to the cylinder. The inner fluid channel extends from the first end to the second end. The pump head and the first end of the elbow are configured to make mechanical and fluid connections with a single linear motion of the pump.

A high-viscosity fluid pumping system includes a reservoir defining an interior for holding a fluid and a pump assembly having an inlet and an outlet. The pump assembly includes a housing defining a chamber, a check valve and a piston. The inlet provides fluid communication between the interior of the reservoir and the chamber. The chamber is in fluid communication with the outlet. The check valve is positioned between and fluidly connected to the outlet and the chamber and permits the fluid to move from the chamber to the outlet. The piston is positioned in the chamber and moves from a retracted position, in which the chamber is in fluid communication with the inlet, and an extended position to move the fluid through the check valve to the outlet. At least one heater is provided to heat the fluid in at least one of the pump assembly and the reservoir.

A pump for use with a material sprayer includes a cylinder, a piston, a pump head, first and second check valves, and an elbow connected to the cylinder. The cylinder and the piston are coaxial with a pump axis. The pump head is configured to make a mechanical connection with the reciprocating drive mechanism so as to allow the reciprocating drive mechanism to reciprocate the piston along the pump axis. The elbow includes a first end, a second end, and an inner fluid channel. The first end is configured to make a fluid connection with the hopper. The second end is configured to be fixed with respect to the cylinder. The inner fluid channel extends from the first end to the second end. The pump head and the first end of the elbow are configured to make mechanical and fluid connections with a single linear motion of the pump.