Knowledge of the advantages and disadvantages of various types of pumps is helpful to the petroleum staff NCO when supervising the use of the pumps and performance of PMCS.
Lesson Description:
This lesson covers advantages and disadvantages of various types of pumps and the performance of PMCS on the pumps.
Terminal Learning Objective:
| Action: | The soldier will acquire knowledge on monitoring PMCS on pumps, verifying appropriate entries on DA Form 2404 (Maintenance Request) and DA Form 5988-E (ULLS)(Equipment Maintenance Worksheet) and correcting deficiencies, observing safety precautions, and identifying environmental considerations. |
| Condition: | Given subcourse QM5094. |
| Standards: | The soldier must score a minimum of 70 percent on the end of subcourse examination. |
As a petroleum supervisor, you must understand the basic workings of the types of power units used in petroleum operations. You must also understand the operating characteristics of pumps in order to properly supervise you subordinates.
There are two types of internal combustion engines: reciprocating and turbine. The reciprocating spark ignition engine is of the gasoline burning type. The fuel is ignited by a spark plug when the piston is at the top of the cylinder. There are two classifications of reciprocating engines: four cycle and two cycle, The four cycle produces more power than the two cycle engine, but it is a much heavier engine than the two cycle. Gasoline engines used in the military are generally used with small equipment such as 100 GPM pumps (four cycle), chain saws, and outboard motors (two cycle).
The compression ignition engine functions the same as the spark ignition except it does not have spark plugs. Heat of compression is the source of ignition. For this reason, the engine is of much heavier construction. As the piston moves in the upward stroke, the air is compressed and heated to approximately 900 to 1000 degrees Fahrenheit. At this point fuel is forced into the chamber by means of an injector and combustion takes place. The compression ignition engine will produce more horsepower and because of fuel injection is much more efficient than the spark ignition engine. The cost is much more than the gasoline engine, but there is less maintenance required. Diesel engines are very well suited for large pumps and stationary applications where low speeds and high horsepower are required. Because diesel engines use heat compression for ignition, they need assistance in order to start in cold weather. This is accomplished by glow plugs or ether injection.
Turbine engines work on the principal of heat of compression, but do not use pistons to create hot air. The air is compressed by the use of compressors and is directed to a combustion chamber where fuel is injected and combustion takes place. The basic design is very simple and there are less moving parts than reciprocating engines. The following are characteristics of turbine engines:
Electric motors are used in fixed facilities because of their lower maintenance and operating cost. Electric motors operate in a magnetic field. When energy is applied, the magnetic field is established and creates a push-pull action which causes the armature to turn.
There are three basic types of pumps used by the Army. These are: reciprocating, rotary, and centrifugal. Reciprocating pumps displace liquid by a reciprocating or back and forth motion. The most common application is a piston or plunger moving back and forth in a cylinder. As the piston moves backward, a suction is created and the liquid is drawn into the cylinder. As the piston moves forward the liquid is expelled. When only one piston is used, it is classified as a simplex pump. When two pistons are used, it is known as a duplex pump, this will move fluid in both directions. Because of their action, they are classified as positive displacement pumps. These pumps create special problems.
The pump you will see the Army use is the ROWPU, because of the high pressure required to pump the water through the system. Advantages of the reciprocating pumps are:
Disadvantages of the reciprocating pumps are:
Rotary pumps are positive displacement pumps in which the main pumping action is caused by rotating gears. As the gears rotate, the fluid is trapped between their teeth and is carried around to the discharge outlet. There are a variety of rotary pumps. In petroleum handling operations, their principal application is in low pressure, low capacity operations. The advantage of rotary pumps is their ability to pull fluid into the housing without the aid of a priming tank or vacuum pump (self-priming). They also have constant discharge characteristics. The only petroleum vehicle that presently uses rotary motion is the M49A2C.
Centrifugal pumps employ centrifugal force as the principle of operation. Simply put, the action of this pump is an impeller rotating in a volute casing. Fluid forced into the eye of the impeller is picked up by the vanes and discharged into the casing by centrifugal force. Because of their simplicity and low cost and ability to operate under a wide variety of conditions, centrifugal pumps are one of the most popular types. Centrifugal pumps that are in use in the petroleum pipeline and TPT operations include:
Centrifugal pumps can be classified or described by:
Centrifugal pumps are used to transfer fuel from storage tanks to truck loading racks, from one tank to another, and to feed pump stations on the main pipeline.