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 The commonly accepted conventional nomenclature and descriptions of liquid supply systems for reciprocating pumps is often misleading and provides an inaccurate description of the pumping action. This nomenclature often describes attributes of the pump that do not exist. Intellectually, we all understand the conventional notations and descriptions, however the concept of the pump being a machine which takes action on a liquid often confuses and deceives the intellect into believing that the pump has control over the amount of liquid being introduced into the pump.

The pump relies upon outside forces to push the liquid through the inlet manifold and inlet valve into the liquid chamber of the pump. The pump cannot pull the liquid into the liquid chamber, as there is no tensile strength to the liquid. The pump merely creates a partial vacuum in the liquid chamber that is then filled by the forces acting upon the liquid on the inlet side of the pump.

Also, please remember when reading this manual, that liquids remain liquids only so long as outside pressure remains high enough to keep the liquid from boiling. If the pressure on the liquid is reduced below the pressure at which the liquid boils at the pumping temperature, the liquid changes to its vapor state and is no longer a liquid. It is the responsibility of the liquid supply system to provide liquid to the pump inlet at sufficient pressure to keep the liquid from boiling during the pumping cycle. Doing this will reduce maintenance on repair of the pump, the supply system, and the discharge system.

This manual is not intended to solve all the problems, which come up in applications involving WGI reciprocating pumps. We do hope it does provide enough insight to allow the reader to place the action of a reciprocating pump in its proper perspective.

(Disclaimer)
Although all the information in this book generally applicable to all reciprocating pumps, the specific data within applies only to Wheatley and GASO pumps.

Safety Precautions:

1. Never start or operate a pump against a closed discharge line. Catastrophic destruction of piping or pump will promptly occur.
2. Avoid starting against a full discharge load. Bring pump up to speed using a bypass, then gradually place pump on line.
3. Bleed air from pump and piping before starting pump.
4. The cradle cover must be in place while pump is running.
5. Stand clear of pump while operating under pressure.
6. Do not operate pump above "maximum design pressure" indicated on metal tag. Operating above the maximum design pressure will result in damage to pump, person or property. Notify WGI at the first sign of a suspected malfunction.
7. Contact WGI immediately if operating conditions or type of service change. Upon request you can receive recommendations to meet the new specifications and a new application tag can be sent.

Before starting a WGI reciprocating pump.

1. Packing for piston and plunger pumps:
   1. Piston Pumps - Piston pump stuffing boxes are not packed when shipped from the factory. These pumps must be packed before starting. If the pump is to be placed in storage before use, the piston rods should be coated with grease to prevent rusting. See the Pump Storage section for other steps to take before placing pump in storage.
   2. Plunger Pumps - These pumps are packed prior to shipment for immediate service. If temporary storage is intended, the plunger must be protected by taking the following steps: rotate the crankshaft slightly more than one revolution, and apply a film of oil to each plunger surface as the plunger moves out of and into the stuffing box packing. Change the position of the plungers periodically/or at least once a week and reapply oil onto each plunger. These steps will help prevent pitting of the plunger from chemical reactions between the packing and the metal surface of the plunger, during periods of inactivity. See Pumps Storage section for more information.
2. Crankcase has been drained by WGI before shipping pump to you. Fill with lubricant as recommended by operating instructions to ensure proper lubrication of gears, chain, crossheads, connecting rods and shaft bearings. Then rotate the crankshaft by hand at least once a week until starting in order to avoid rust formation from water condensation on unpainted internal parts. Shaft bearings requiring a separate oil bath have been filled at factory with recommended lubricant but should be checked for proper oil level before starting. Check oil levels daily. Change lubricant at least every six months. Drain and thoroughly flush the crank case and bearing housings when making this change.
3. Read Operating Instructions and Maintenance Suggestions or Operator Manual for the specific pump model. If misplaced or lost, please contact your nearest WGI distributor or contact WGI direct for a copy.
4. A pressure relief valve must be installed in the discharge piping between the pump and any other pipe fittings. See page 40 set pressure suggestions.
5. All belt and coupling guards must be firmly in place.
6. Be sure that all pipe joints and fasteners are definitely tight before putting the pump into operation.
7. Check connecting rod bearings for proper adjustment - according to operating instructions.
8. Check main bearings for proper adjustment - according to operating instructions.

After starting a WGI reciprocating pump.

1. New non-adjustable lip type packing rings (plunger pumps only) may be expected to leak slightly for a day or so, but will gradually seat. The packing gland must be retightened and periodically checked after the packing has seated. DO NOT attempt to adjust packing while pump is running.
2. Piston pump packing is available in several different configurations. All are adjustable type packing. Care must be taken to ensure that this packing is not over tightened. On most installations, a very slight drip is desirable to aid in lubrication and as visual proof that the packing is not too tight.
3. After Two (2) Hours Operation (also refer to Appendix I)
   1. Check all the crank end connecting rod bearings for proper adjustment. Check connecting rod bolt nut torque and adjust if necessary.
   2. Check lubricant level and pressure gauge (if forced lubrication system is furnished).

How a Reciprocating Pump Works

A reciprocating pump is a positive displacement mechanism, liquid discharge pressure being limited only by the strength of the structural parts. Liquid volume or capacity delivered is constant regardless of pressure, and is varied only by driver speed, speed reduction, and/or plunger/piston size changes.

Reciprocating motion is imparted to a plunger/piston by a slider crank linkage which results in a piston motion closely approximating simple harmonic motion, as shown in Appendix B. This reciprocating motion alternately lowers the pressure in front of the plunger/piston when filling the pump, and increases the pressure when emptying the pump. The incoming liquid opens the suction/inlet valve. At the same time the discharge valve is held closed by the downstream line pressure. Outgoing liquid closes the inlet valve and opens the discharge valve. This simple mechanism provides high volumetric efficiency, approximately 95 percent, for most incompressible liquids.

Characteristics of a WGI reciprocating pump are;

(a) Positive liquid displacement

(b) High pulsations caused by the sinusoidal motion of the plunger/piston

(c) High volumetric efficiency

(d) High mechanical efficiency

(e) Low pump maintenance cost

1. Plunger or Piston Rod Load

Plunger or piston rod load is an important power end "design" consideration for WGI reciprocating pumps. Rod load is the force caused by the liquid pressure acting on the face of the plunger/piston. This load is transmitted through the adapter or piston rod to the crosshead, then to the crosshead pin, wrist pin bushing, connecting rod, crank shaft, main bearings and power frame. This load is directly proportional to the discharge gauge pressure and the square of the plunger/piston diameter.

Occasionally, allowable liquid end pressures limit the "allowable" rod load to a value below the "design" rod load. It is important that liquid end pressure DOES NOT exceed WGI's latest published recommendations.

Rod loadsare not generally used when "applying" the pump. They are used to establish the power frame design - not to determine the allowable pressures, in most cases, for each size plunger/piston.. Also see the Sizing pumps in high inlet pressure conditions section 

1. Calculations of Volumetric Efficiency

Volumetric Efficiency (E_V) is defined as the ratio of actual pump capacity to ideal pump displacement. The E_V calculation depends upon the internal configuration of each individual liquid end cylinder, plunger/piston size, and the liquid being pumped. Given full details regarding differential pressure, pumped liquid mixture, and expected temperature rise on the discharge stroke - WGI can calculate this efficiency.

1. Calculating E_V for Water

See TABLE 4 Page A31 for the water compressibility chart. An example of volumetric efficiency calculation for water is also shown.

2. Calculating E_V for Hydrocarbons

See TABLE 6 Page A34 for the physical properties of hydrocarbons. For compressible liquids such as these, horsepower calculations are slightly more complex than for incompressible liquids. However, the magnitude of the horsepower required will be slightly less than if calculated for the full displacement.

3. DISPLACEMENT TABLE

Material Selection Chart for Plunger Pumps

NOTES:

1. Bronze parts should not be used in liquid end.
2. Contamination of pumpage by packing lubricant is acceptable, use lubricated non-adjustable packing and lubricator.
3. Use metal plunger with ceramic coating when temperature exceeds 180 deg F or lithe plunger may be exposed to temperature differential of lOooF.
4. Check suitability of packing for pumping temperature.
5. For temperatures down to oaF use A36 steel billet or A105 forging
6. For temperatures from 0 degrees F to -20 degrees "F use normalized A36 steel billel For temperatures from _20∞F to -50"F use 4340 steel billet.
7. For temperatures below -50"F use 316 stainless steel or nickel-aluminum-bronze.
8. Brake fluid. low temperature transmission fluid, or refrigeration oil should be used as packing lubricant at colder temperatures.
9. Delrin or Celcon Disc type valves may be used for pressures up to 1500 psi and temperatures up to 150 degrees "F; Monel valve seats may be used when pumpage does not attack bronze, titanium disc for high temperature and low NPSHR application, or stainless steel disc for most of the pressure ranges.
10. Hydrocarbons include; Butane, Ethane, LPG, Methane, Pentane, Propane, etc.
11. For pumps in intermittent service, steel or aluminum-bronze liquid end may be used if liquid end is immediately flushed after each use. immediately flushed after each use.
12. Material recommendations apply only to non-aerated saltwater Only.
13. Steel or ductile iron liquid end may be acceptable - check customer's requirement
14. Not FDA approved.

PACKING NOTES: Where lubricated, Non-adjustable packing is recommended, it has temperature limitations of -40 degrees F to 250 degrees F and pressure limitation of 3000 psi (base fibers are nitrile and poly/colton).

Piston Pumps

Types of Reciprocating Pumps

Single acting plunger pumps fill on the reverse stroke and exhaust on the forward stroke. The liquid end is sealed from the atmosphere by packing around the plunger. This type of pump is commonly called an "outside packed" pump. WGI manufacturers these pumps with either one, two, three, or five plungers/cylinders. This type of pump is horizontally operating.

Single acting piston pumps exhaust only during the forward stroke of the piston, that is, during one half of the revolution.

Double acting piston pumps fill and exhaust on the same stroke, one side of the piston facing the end of the cylinder being filled and the other side of the piston exhausting the other end of the same cylinder. This type of pump is commonly called an "inside packed" pump where the "packing" is a series rings or a set of rubbers which stop leakage from one side of the piston to the other. The piston rod diameter is relatively small compared to the diameter of the piston and is easily packed to avoid leakage. This type of pump is also horizontally operating.

Where Reciprocating Pumps are Used

WGI reciprocating pumps are used in all applications requiring a combination of high differential pressure and relatively low capacities.

Single acting plunger pumps for high capacities and high pressures at high rpm, low initial costs, and average lifetime.

Double acting piston pumps for high capacities and moderate pressure, low rpm, moderate initial cost and extremely long life.

Sizing and Selecting a Reciprocating Pump

In order to properly select and size a reciprocating pump, WGI requires the following information for most applications.

1. Characteristics of the liquid
   1. Liquid composition (including % and type of solids present)
   2. Outlet and inlet pumping temperature
   3. Specific gravity of liquid at outlet and inlet pressures & temperatures
   4. The corrosives and/or abrasives present
   5. Vapor pressure at pumping temperature
   6. Viscosity of liquid at pumping temperature
2. Desired pumping capacity, at pumping temperature, in units of: gallons per minute, barrels per hour, or barrels per day.
3. Whether a future or alternate capacity is contemplated for the pump(s).
4. Pressure conditions required.
5. Liquid pressure at the pump discharge.
6. Liquid pressure at the pump inlet/suction (NPSHA).
7. Whether a future or alternate pressure condition is contemplated for the pump(s).
8. Electrical or other area hazard(s).
9. Flange rating required for the operating pressures and temperatures, if other than standard.
10. Preferred/specified metallurgy of major parts.
11. Driver type, to include power characteristics; electrical voltage/phase/hertz or gasoline/diesel fuel.
12. Space limitations/constraints.
13. Site ambient temperature range.
14. Indoor or outdoor location.
15. Pump storage

In order to prevent permanent damage to pumps which are placed in storage, the following procedures are recommended:

Short Term Storage

Recommended for period less than 6 months and a minimum requirement for any exported pumps or pump package units without customer procedures.

1. Where possible, place pump in an enclosed storage facility. If enclosed storage is not available, cover the entire pump and associated exposed attachments with a heavy tarpaulin.
2. Remove crankcase cover and fill the crankcase with lubricant (approved and specified on pump applications tag).
3. Replace crankcase cover.
4. Drain all fluids and remove; valve covers, cylinder heads, and inlet and discharge flange plugs.
5. Apply a film covering of lubricant to all exposed parts.
6. Remove cradle cover and coat plunger or rod surface with lubricant.
7. Replace valve covers, cylinder heads and inlet and discharge flange plugs.
8. Rotate crankshaft 10 complete turns and reapply liquid end protection, including plungers (as described in steps d, e, and f above), weekly.
9. Check for oil leaks around pump and replace gaskets or seals immediately if necessary.

Refer to engine, motor, gear reducer, etc. manufacturer's instructions for storage procedures.

Long Term Storage

Recommended for a period exceeding 6 months.

1. The pump and parts should be stored in a clean, dry location, free from temperature extremes, in an approximately level position and without distortion.
2. It is desirable to completely fill the power end (crankcase cavity, etc.) of the pump with the approved lubricant. Such a fluid level would ensure all parts within the power end are protected. To fill the power end, remove the hand cover and fill with lubricant. Be sure to replace the hand cover. Service the remainder of the pump as directed above in steps d-h.
3. Inspect periodically for possible oil leakage and replace gaskets or seals immediately if necessary.

Caution:Before placing the pump, engine, gear reducer, etc. into service, fill the crankcase with the manufacturer recommended lubricant and check for proper lubricant level.

Caution:Double acting piston pumps, having steel or file hard steel piston rods, require special attention.

Remove liquid end stuffing box packing in pumps having piston rods in these materials as they are subject to chemical and atmospheric corrosion, if left in contact with the packing.

Exposed sections of these rod materials must protected by a coating of heavy grease or rust preventative.

Each time the pump is rotated during storage, this coating must be checked and reapplied, if needed.

A heavy coating of lubricant is also recommended immediately after servicing or recommissioning the liquid end.

1. Sizing a WGI Pump for High Inlet Pressure Conditions
2. For double acting piston pumps, no derating is required.
3. For a single acting plunger pump, where the rod load due to inlet pressure is less than 20% of full plunger/rod load, no derating required.

3. For a single acting plunger pump (with standard bronze wrist pin bushings), where the rod load due to inlet pressure is greater than 20% of full plunger/rod load, derating is as follows:
4. For a single acting plunger pump (with optional wrist pin roller/needle bearings), where the rod load due to inlet pressure is greater than 20% of full plunger/rod load, no derating is required if both of the following requirements are met;
5. For triplex pumps, add two-thirds the inlet/suction pressure to the discharge pressure in selecting the pump maximum plunger pressure.
6. For quintuplex pump, add two-thirds the inlet/suction pressure to the discharge pressure in selecting the pump maximum plunger pressure.

a.)Inlet/suction pressure is less than 50% of the maximum plunger pressure rating

b.) Discharge pressure is less than the maximum plunger pressure rating.

Pressure

Liquid pressure is defined as the normal component of force per unit area. In common practice and general function, pressures are frequently measured in pounds force per square inch (lbf/in²). Gauge pressure (psig) is the difference between absolute pressure (psia) and the atmospheric pressure (P_a). Appendix A, Table 7 shows the relationship between atmospheric pressure and elevation. Vapor pressure is the absolute pressure exerted by the liquid and its vapor to maintain an equilibrium condition at a given temperature of the liquid. 

Head

The English unit for measuring head is feet. The equation, expressing pressure (psi) in units of feet, is:

Head = psi x 2.31

S.G.

Where,

S.G. = Specific Gravity @ pumping temperature.

at 20 psi pressure.

Head = 20 x 2.31 = 3.39 ft.

13.6

Viscosity

Basic metric viscosity units are the poise (absolute/dynamic viscosity) and the stokes (kinematic viscosity). More customary expression of these units are centipoise and centistokes respectively, each equal to 1/100th the of basic metric viscosity unit. The relationship between the English units for medium viscosity liquids,

 SSU (Saybolt Universal Seconds), and metric absolute viscosity is:

n (absolute viscosity, centistokes) = 0.22 (SSU) - 180

(SSU)

Introducing the mass density of the liquid (r) allows the expression of the relationship between absolute viscosity to Kinematic viscosity as follows:

m (Kinematic viscosity, centipoise) = rn

1. Frictional head losses

Pipe, valves, fittings, hoses, and meters installed in the liquid supply piping system generate resistance to the liquid flow. The friction head is the hydraulic pressure required to overcome frictional resistance of a piping system. The Table in Appendix C shows an equivalent length in feet, of 100 percent opening valves and fittings. Pressure drop in liquid lines versus liquid flow rates is shown in Appendix D.

1. Reynolds Number

The Reynolds Number (R_e) is used in closed conduit/pipe flow, deals with the viscous force in a liquid, and is defined by the following equation:

R_e = r₁ d_f n₁

m₁

Where,

R_e = Reynolds Number

r₁ = liquid density at flowing temperature, lbm/ft³

d_f = pipe inside diameter, feet

n₁ = liquid flow velocity, ft/sec

m₁ = liquid viscosity

(centipoise divided by 1488 or centistokes multiplied by S.G. then divided by divided by 1488)

Customarily; turbulentflow occurs when the R_e is greater than 3000, laminar flow occurs when the R_e is less than 2000. The transition period is when the R_e is between 2000 and 3000.

Acceleration head

Whenever a column of liquid is either accelerated or decelerated, pressure surges exist. This condition is found on the suction/inlet side, as well as discharge side, of a reciprocating pump. Not only can the surges cause vibration in the inlet line, but they can restrict and impede the flow of liquid and cause incomplete filling of the inlet valve chamber. The magnitude of the surges, and how they will react in the system, is impossible to predict without an extremely complex and costly analysis of the system. Since the behavior of the natural frequencies in the system is not easily predicted, as much of the surge as possible must be eliminated at the source. Proper sizing, installation and charging of a dampening device will absorb a large percentage of the surge before it travels into and through the system and cause trouble. The function of the device is to absorb the peak of the surge and feed it back at the low part of the cycle. The preferred position for the device is in the liquid supply line, as close as physically possible to the reciprocating pump, or alternately attached to the blind side of the pump inlet. In either location, the surges will be significantly dampened and the possibility of harmful vibrations considerably reduced.

The experimental formula for calculating acceleration head is:

h_a = L V n C and V = GPM K g (2.45) (ID)²Where,h_a = acceleration head (ft.)L = length of liquid supply line (ft.)V = average velocity in liquid supply line (fps)n = Pump speed (rpm)C = Constant depending on the type of pump (see page A35)K = liquid compressibility factor:K = 2.5 for relatively compressible liquids (ethane, hot oil)K = 2.0 for most other hydrocarbonsK = 1.5 for amine, glycol and waterK = 1.4 for liquids with almost no compressibility (hot water)g = standard gravity = 32.2 ft/sec²ID = inside diameter of pipe (in.)

benefits in avoiding harmful vibrations.

NPSHR (Net Positive Suction Head Required)

The NPSHR is the head of liquid, in feet, required at the centerline of the liquid end inlet/suction connection to completely fill each cylinder on the reverse/suction stroke. It is the feet of liquid necessary to;

1. overcome the frictional losses through inlet manifold, valves and liquid chamber,
2. overcome the valve weight and spring force acting on the valve,
3. overcome the valve velocity head losses,
4. accelerate the liquid from rest to required velocity.

NPSHR is a function of the liquid and pump characteristics (stroke, plunger size, liquid end design, and operating speed).

NPSHR is usually determined by test or estimated by computation. Figure 55 and 56, on pages A36 and A37 respectively, show the liquid supply system relationships for open and closed supply tanks.

NPSHA (Net Positive Suction Head Available)

NPSHA is the total inlet head from the system at the pump inlet connection minus the vapor pressure of the liquid at the pumping temperature. It is a function of the supply system and the liquid and pump characteristics (stroke, plunger size, liquid end design, operating speed).

The pump characteristic is important to both supply system and NPSHR. A liquid supply system designed without consideration of the pump characteristics has not been properly designed.

Pump Cavitation

A WGI reciprocating power pump is a device to move liquid under specified operating conditions. If the liquid is not arriving at the inlet side of the pump promptly, evenly, and with the least amount of resistance; the pump cannot operate efficiently, nor can it move the liquid through the discharge system smoothly. A poor liquid supply system to the inlet side of the pump will create pump cavitation (where liquid moving through the pump vaporizes rapidly wherever the local absolute pressure falls to, or attempts to fall below, the liquid vapor pressure). Cavitation can cause premature failure of the pump valve, piston or plunger packing, pitting of the cylinder walls, and damage to the pump and system by subjecting all parts to undue stresses. Consider the interactions between a piston and the liquid it pumps. The piston must stay in contact with the liquid through its entire stroke.

For reciprocating power pumps, plunger/piston velocity varies sinusoidally with crankshaft position. Maximum velocity occurs approximately at mid-stroke and zero velocity occurs at both ends (full forward position and full reverse position) of the stroke. Under certain inlet conditions, liquid looses contact with the piston and creates a cavity. When the piston slows, and the liquid catches up with the piston, collapsing of the cavity will occur. This cavitation creates shock waves that travel throughout the pump and pumping system, generating noise, vibration and wear.

Even if velocity-matching requirements are met, pressure at the pump inlet must be high enough to prevent gas formation/separation.

Liquid Supply System Relationships

Open Supply - Elevated Inlet Situation

If atmospheric pressure available at site is greater than the equation (NPSHR + P_v + h_f + h_a), it is possible to install the pump inlet above the level of the liquid. The maximum distance (I_e(max)) the pump inlet can be placed above the liquid level is determined by the following equation

converted to units of feet:

I_e(max) = P_a - (NPSHR + P_v + h_f + h_a)

Where,

I_e = elevation distance from the center line of the pump inlet connection to the liquid level, feet

I_e(max) = maximum inlet elevation distance, feet

P_a = atmospheric pressure available at site

NPSHR = net positive suction head required (specified by pump manufacturer)

P_v = absolute vapor pressure (@ pumping temperature) plus 7 feet

h_f = friction losses through pipe and fittings, feet

h_a = acceleration head, feet

To convert psi (pounds per square inch) to feet of head, multiply psi by 2.31 then divide by specific gravity (S.G.).

feet of head = psi x 2.31

Specific Gravity.

If it is found that the actual distance which the pump may be installed above the liquid level is less than the maximum calculated distance, then NPSHA is equal to the equation NPSHA - P_a - (P_v + h_f + h_a + I_e), converted to feet.

In order to find whether the pump can be installed above the liquid level, a comparison of P_a and the evaluation of the equation (NPSHR + P_v + h_f + h_a) is necessary. If P_a is found to be the greater, the pump may be placed above the liquid level.

Supply System Piping Design

1. Pump should be located as close to the liquid supply as possible.
2. Use full opening gate valves and avoid constricting valves.
3. The ideal piping arrangement is short and direct, using no ells. Should ells be required, use 45 degree long radius instead of 90 degree ells.
4. If a reducer is required in inlet line between the main line and pump, use an eccentric reducer rather than concentric (with straight portion on top to help avoid air pockets trapped in inlet line).
5. Slope line uniformly to pump from liquid supply to avoid air pockets.
6. By-pass design should take liquid back to liquid source and not into inlet line.
7. Inlet line should be firmly anchored or buried to avoid putting a strain on the pump and help prevent system vibrations from acting directly on the pump.
8. For inlet lines leading directly to the pump, select a size line so that the velocity of the liquid will not exceed one foot per second, or one that is two sizes larger than the pump inlet connection, whichever gives the lower line velocity.
9. Install a properly sized charging pump in the inlet line as close to the pump as possible.
10. Install a full opening gate valve on the inlet line to allow for pump maintenance.
11. Inlet PCT (pulsation control tool).

Discharge Piping Design

1. The insertion of a pressure relief valve (PRV) of suitably sized for the full pump capacity and set fully open at a pressure above the required operating discharge pressure of the pump, is mandatory for safe operation.

The PRV should be placed in the discharge line, as close as possible to the pump and before any other valves. The PRV outlet should be piped back to the liquid source.

Suggested trial set pressures of pump PRV's:

2. Install a full opening gate valve on the discharge line to allow pump maintenance.
3. Install a check valve on discharge line to protect pump from harmonic vibration from other installations on the line.
4. Install a properly sized discharge PCT to reduce vibration and piping damage.
5. Securely anchor discharge lines.
6. When possible, run discharge lines straight for at least ten feet before bending.
7. Install a by-pass valve to aid in pump start-up.
8. Use 45 degree long radius ells.

Recommended Safety Devices

1. Hi-Lo oil level control & oil temperature gauge.
2. High temperature control.
3. Oil pressure control.
4. Low liquid level control (to control the NPSHA).
5. Low discharge pressure shut-down.
6. High discharge pressure shut-down.
7. Pre/Post lube of force feed power end lubrication system.