Figure 25 - Schematic Flow DiagramNOTE: Beginning in November, 1967 (11N Date Code) Standard Type 40 pumping units had a filter instead of a strainer. It is a Wix PC-314P and is obtainable as a shelf item in most equipment stores. (The strainer was used in all Code D heavy duty pumping units, and was also available on standard units by specifying Code 422.) With use of the new filter, the aligning stud for the strainer was eliminated to give maximum flow through the one-inch hoe. Also, a new cover, which is held in place by three bolts, was required. The strainer can be used in new units, but the filter should not be used in units with the center stud because adequate flow will not be available.
Before studying the various components of the Bennett pumping unit, air eliminator, and meter, it is essential to visualize the travel of the liquid through the various units. See the schematic diagram in Figure 25.
Figure 25 - Schematic Flow Diagram
1. The gasoline is drawn from the underground storage tank through the strainer screen or filter (1).
2. The rotary vane pumping unit (2) impels the gasoline on into the air eliminator.
3. Gasoline enters the air eliminator (3) near the top and spirals around to the bottom and down to the control valve.
4. The control valve (4) is opened by the liquid pressure and the gasoline is pumped up to the meter. A built-in relief valve relieves pressure caused by hot weather expansion.
5. Gasoline passes through the meter (5) and on out through the hose.
6. When the nozzle is closed and the pump motor is still operating, the liquid back pressure opens the bypass valve (6) which bypasses or shunts the liquid back to the pump intake port. The liquid is then re-circulated until the nozzle is reopened or the motor is shut off.
The Type 40 pumping unit was manufactured during the time when pre-pay operation was not prevalent. To add prepay to a pump with a Type 40 pumping unit, an adapter with a diaphragm valve was created. This adapter mounted to the outlet of the meter and was field installed.
The Flow diagram in Figure 26 shows the Type 40 running with solenoids de-energized (no flow).
Figure 26 - Solenoids De-energized (No Flow)
1. Product from the pumping unit flows through the meter to the inlet (1) of the prepay adapters. Product flows to and pressurizes the back of the diaphragm valve (2).
2. Product from the meter flows through tube (5), through the high flow solenoid, through tube (6) and to the front (3) of the diaphragm valve.
3. Equal pressure is now applied to the front and back of the diaphragm valve. The spring (4) exerts greater pressure on the front of the diaphragm valve causing it to close and preventing high flow.
4. At the same time, product from the meter flows through tube (8) to the low flow solenoid. The low flow solenoid being de-energized prevents product flow to tube (9) and prevents low product flow.
The flow diagram in Figure 27 shows the Type 40 running with solenoids energized.
Figure 27 - Solenoids Energized
1. Product from the pumping unit flows through the meter to inlet (1) of the prepay adapter and pressurizes the back of the diaphragm valve (2).
2. Product from the meter flows through tube (3) to the high flow solenoid. When the high flow solenoid is energized, product flow from tube (3) to tube (4) is prevented.
3. When the high flow solenoid is energized product pressure is relieved off the front of the diaphragm valve (5) via tube (4) through the solenoid, through tube (6) and out to the hose.
4. Higher product pressure on the back of the diaphragm valve (2) overcomes spring tension (7) and pushes the diaphragm valve into its open position. The diaphragm valve in its open position allows high product flow.
5. At the same time, product from the pumping unit flows through tube (8), through the low flow solenoid, through tube (9) and out to the hose.
6. In prepay or local preset operation, the high flow solenoid is de-energized at a point before final sale is reached. The low flow solenoid is energized from the beginning to the end of the sale. This allows the pump to slow before final sale is reached which prevents overruns.
The purpose of using directional valve assemblies on single product, two hose units is to prevent delivery from an unauthorized hose when the other one is in use.
Figure 28 shows the configuration of a Type 40 pumping unit as a single product unit with two hoses (pump running and the solenoids de-energized).
Figure 28 - Solenoids De-energized
1. Product from the pump flows into the directional valve casting and pressurizes the back of the diaphragm valve (1).
2. Product from the pump flows into the directional valve casting and through tube (2) to the top of the solenoid. Because the solenoid is de-energized, product flows from tube (2), through the solenoid, into tube (3) and pressurizes the front of the diaphragm valve (4).
3. Equal product pressure is now realized on the front (4) and back (1) of the diaphragm valve. Added spring (5) exerts greater pressure on the front of the diaphragm valve causing it to close and preventing product flow.
Figure 29 shows the configuration of a Type 40 pumping unit as a single product unit with two hoses (pump running and the solenoids energized).
Figure 29 - Solenoids Energized
1. Product from the pump flows into the directional valve casting and pressurizes the back of the diaphragm valve (1).
2. Product from the pump flows into the directional valve casting and through tube (2) to the top of the solenoid. When the high flow solenoid is energized, product flow from tube (2) to (3) is prevented.
3. When the high flow solenoid is energized product pressure is relieved from the front of the diaphragm valve via tube (3) through the solenoid, through tube (5) and to the hose.
4. Higher product pressure on the back (1) of the diaphragm valve overcomes the spring tension (6) and pushes the diaphragm valve into its open position. The diaphragm valve in its open position allows full product flow for that hose.
Due to the greater GPM required of heavy-duty or code D pumps over standard, a specially designed pumping unit is used. This heavy-duty pumping unit is similar in appearance to a standard unit, but it can be easily identified by a large letter "D" stamped in the upper left hand corner of the casting, on the pulley side, as shown in Figure 30.
Figure 30
The bypass adjusting nut is also a means of identification. As shown in Figure 31, the bypass adjusting nut on a Code D unit with heavy-duty bypass valve and spring has two hexagonal portions, while on units with standard bypass valve and spring it has only one hexagonal portion.
Figure 31
NOTE: Models 3027, 3127, 4027, 4127, and 3376 (twin single product pumps) have heavy-duty rotors (reference Figure 5 above) and standard bypass valves and springs.
In addition to the external means of identification, there are certain internal parts that are not the same in the two types of pumping units. The higher delivery rate of the Code D pump is obtained by a greater displacement between the bore and rotor, as shown (slightly exaggerated for purpose of illustration) in Figure 32. To obtain this, the rotor is smaller in diameter in a heavy-duty unit and can be easily identified by its three relief holes for each blade slot.
Figure 32
Only one relief hole is used in a standard rotor. See Figure 33. To compensate for the variation in rotor sizes, the pumping units are machined differently. The heavy-duty rotor blade is larger than the standard, as shown in Figure 34. Therefore, rotors, blades, and pumping unit castings are not interchangeable.
Figure 33
Figure 34
NOTE: The bypass valves and springs will fit either pumping unit, but should not be interchanged. All other parts in the pumping unit and air eliminator assembly are the same in both standard and heavy-duty units.
The air eliminator is a combination air and vapor separator, liquid stabilizer, and pressure relief chamber all combined into one unit. Without it, nozzle valves and gasket joints would leak, and hose and see-gage glasses would burst under the effects of the summer sun. Displacement meters, no matter how accurately built, could not be made to measure accurately unless the vapors, normally present in gasoline, and the air induced by deficient installation conditions, can be eliminated and discharged before reaching the meter.
The air eliminator meets every requirement for perfect air elimination, yet it is compact and simple in construction. It contains two separate chambers; the pressure chamber that is always filled with liquid and the atmospheric chamber containing only a small amount of condensed gasoline vapors which overflow through the vapor release jet. This liquid is maintained at a minimum level by the suction return float valve. A vent pipe at the top of the atmospheric chamber carries vapor outside the pump housing. This positive method of air elimination can be readily understood by referring to the cutaway views in Figure 35.
Figure 35
The following essential factors of the air eliminator should be carefully noted.
1. The vapor release jet is located at the highest point in the pressure chamber where any vapor or air would normally collect.
2. The discharge opening and control valve are located at the lowest point in the pressure chamber which would normally contain solid liquid.
3. The suction return valve is located at the lowest point or sump in the atmospheric chamber.
4. The vent opening to the outside atmosphere is located at the highest point in the atmospheric chamber.
5. Eliminator and pump unit are combined into one unit.
6. Liquid is delivered from the pump into the midpoint of the pressure chamber in a swirling motion, thus giving vapors an opportunity to separate and rise easily to the top. Pure liquid only is forced to the bottom.
7. The variable orifice valve and float in the pressure chamber normally keeps only the small jet open, but under excessive vapor conditions, it automatically opens the large jet to permit the escape of larger volumes of vapor.
8. The control valve is designed to perform three functions: (a) it maintains pressure against the flow of liquid to help force out vapor; (b) it prevents liquid from dropping back from the meter; and (c) it contains an internal relief valve to prevent excess expansion pressure from bursting the hose and see-gage.
Only under the most severe conditions should any service be necessary on any part of the air eliminator. Both float valves have positive lever action--tapered valve close into seats. The control valve has a composition disc seating against the ground surface of the pump body.
Should damage occur to the pressure chamber cover, the float could be held in the down position. This could cause an excess amount of liquid to enter the atmospheric chamber and possibly flood it. The result would be a discharge of liquid from the vent tube while the pump is in operation.
Should the float in the atmospheric chamber stick in the down position, the suction valve will remain closed and liquid will be discharged from the vent tube.
Should the float in the atmospheric chamber stick in the up position, the suction valve will remain open, thus reducing flow and a suction can be felt at the end of the vent tube.
Water is harmful to any pump, but not as great in a Bennett pump because there are no points where it can settle. It is a self-cleaning unit; however, it is a well known fact that valves exposed to water will eventually rust. In this event, it is recommended that all valves be cleaned. A water condition may mean the repairing of a broken line or fill cap and pumping any accumulation of water from underground storage tanks with a hand pump.
Ordinarily, the servicing of the suction return float valve can be accomplished by removing the bypass valve cover plate. The pressure valve can be serviced by removing the pressure chamber cover at the rear of the pump housing.
The purpose of the bypass valve is to relieve back pressure when the nozzle is closed and the motor is still operating. Thus, the valve, when open, stops the pumping of gasoline from the storage tank. The liquid in the pumping unit is bypassed or circulated until the nozzle is again opened.
The bypass valve has good self-cleaning action; however, foreign matter on the valve seat or in the dashpot could interfere with proper seating and result in slow or no delivery. If this happens, the valve is very accessible for removal and cleaning. The valve cover is labeled for identification.
The Type 40 pumping unit originally employed a bronze bypass valve. Units containing the bronze valve are identified by the use of an adjustable bypass valve cover (See Figure 36). New style bypass valves are made of Delrin (See Figure 37). Pumps with the new valve were marked Code 412 on their I.D. plate.
A Delrin bypass valve can be used to replace a bronze bypass valve (which are no longer available), if new bypass spring and new bypass cover are installed. These parts are included in Kit KR-0165. See Figure 38.
How to Adjust Bronze Bypass Valve
The original factory bypass setting on a new pump is adequate for most filed installation. (The factory adjustments for both standard and heavy-duty pumps are shown in Figure 36.) Changing these adjustments is discouraged unless unusual installation conditions are encountered. To compensate for varying installations, the bypass valve is adjusted only by means of the adjusting screw (1). Under no circumstances should the bypass spring be stretched. This will exert uneven pressure on the valve and increase wear. If two turns of the adjusting screw do not affect the pumping characteristics, the problem is not one of bypass valve adjustment.
Remove the small brass cap (2) which acts as a seal around the adjusting screw (1). Hold the adjusting screw stationary with a screwdriver while unlocking the locknut (3). Holding the locknut (3) stationary, turn the adjusting screw (1) clockwise to increase or counterclockwise to decrease spring tension until normal delivery speed is attained. Too much tension on the spring will overload the motor during the bypassing process and may also detract from the normal, quiet operation of the pump. When the desired adjustment has been made, tighten the locknut (3) and reinstall the brass cap (2).
Figure 36 - Bronze Bypass Valve
Delrin Bypass Valve
NOTE: If valve adjustment is desired, a washer may be placed over the spring boss on the cover to increase spring tension. The boss is purposely short to prevent excessive tension on the bypass valve that could cause sufficient back pressure to overload the electric motor.
The same bypass valve is used in both standard and heavy-duty (Code D) pumping units. Bypass valve springs are not interchangeable between standard and heavy-duty pumping units. No noise eliminating dashpot plunger is required on this Delrin bypass valve due to its construction and light weight.
Figure 37 - Delrin Bypass Valve
Figure 38 - Bypass Valve Kits
Inspecting and Cleaning the Bypass Valve
1. Bypass Plunger (Bronze Bypass Valve Only)
The valve plunger (1) is a precision fit into the dashpot (2); therefore, extreme care must be used when cleaning this portion of the valve. See Figure 39. Clean the plunger surface with crocus cloth only. Emery paper, sand paper or a file will cut too deeply and impair efficiency of the valve. Also, the dashpot (2) should be flushed with gasoline or blown out with compressed air. Note that there is a gasoline-filled chamber of sufficient length at the end of the dashpot which cushions the valve for quiet operation during the bypassing process.
Figure 39
2. Guide Surfaces
The valve is kept in perfect alignment by the fluted guides (3). See Figure 39 above. Examine for possible foreign deposits and clean with fine emery paper only.
3. Seating Surfaces
A bronze valve that is seating properly will show a hairline shiny ring completely around the seating surface. If it does not have a completed ring, examine the seating surface on the valve for possible foreign deposits and remove with a light application of emery paper. To clean the seating surface and dashpot (2) in the pump casting, a special cleaning tool (Part No. SK-2-151) shown in Figure 40 was recommended for both style valves. The tool is no longer available from Bennett. However, some long time distributors may still have this piece of equipment in their service area.
Figure 40 - Bypass Valve Seat and Dash Pot Cleaning Tool
The original control valve was constructed of bronze. Later production of the Type 40 pumping unit used Delrin control valves. The Delrin valve directly replaced the bronze valve and is the only type available.
Operation of Control Valve
Some of the principles of the bypass valve are included in the construction of the control valve.
The inner end (1) (See Figure 41 or 42) forms a plunger that fits into a dashpot in the air eliminator body, providing smooth operation. This plunger end also acts as a guide, together with the four "fins" or guides (2) at the center of the valve to always keep the valve in alignment. A composition washer (3) provides a seating surface and the throttle plate (4) allows the valve to be held open by the flow of liquid with much less effort than is required for its initial opening and also helps provide for positive, quick closing of the valve.
Figure 41 - Bronze Control Valve
Figure 42 - Delrin Control Valve
Seating of Control Valve
The control valve can be held off its seat by corrosion or gum deposits on the valve cavity or by foreign particles embedded in the composition washer (3). (On pumps with see-gages, if the glasses are only partially filled, it will indicate that the control valve is not seating properly, thus allowing the liquid to drain down from the see-gage, meter and adjoining piping through the control valve opening into the atmospheric or non-pressure section of the air eliminator. When the pump motor is started, computer jump will also result as the vacancy is being filled. To determine if there is a slow leak (not always evident by emptying of the see-gage glasses) we recommend that a test be made with a pressure gauge.
To do this, install the pressure gauge in the drain plug hole in the control valve cover. Start the pump and pump five gallons of gasoline. Then, close the nozzle, shut off the motor and watch the gauge. If pressure holds constant or falls so slowly it is unnoticeable, the control valve is seating properly and need not be removed. However, if pressure drops rapidly, the valve is not seating and should be removed and thoroughly cleaned.
Removing and Cleaning the Control Valve
Remove the control valve cover, being sure to exert slight hand pressure against the cover when taking out the last cap screw. (See Figure 42 above). Spring tension may force the cover off and cause it to drop into the pit under the pump. Be careful not to damage the cover gasket or it will have to be replaced. Remove the spring and valve and clean off the valve with crocus or "00" emery cloth.
Examine the composition washer (3) for foreign particles or marks left by them. To polish the washer, hold the valve in one hand, gasping the valve just behind the throttle plate (4). Hold crocus or "00" emery cloth in the other hand, cupping it around the valve so as to contact as much of the edge of the washer as possible. Polish with a twist or twirling motion--pressing lightly and carefully as the washer must be perfectly concentric to seat properly. Pressing too hard may cut too deeply into the composition washer.
Wash the valve in gasoline before replacing it to be sure it is clean. Before installing the control valve in the pump, inspect the cavity for possible foreign matter.
A special cleaning toll (Part No. SK-2-154) shown in Figure 43 was recommended for cleaning the valve seat and dashpot in the pump casting. The tool is no longer available from Bennett. However, some long time distributors may still have this piece of equipment in their service area.
Figure 43 - Control Valve Seat and Dash Pot Cleaning Tool
Possibility of Control Valve Being Stuck in a Closed Position
This rare condition is always the direct result of neglect in keeping the pumping system free of excessive water which finally leads to seizure of the control valve. It may also occur in pumps that are out of service for extended periods. If the control valve sticks in a closed position, pumping failure will result.
Operation of Expansion Relief Valve
Since the expansion of gasoline in warmer climates or during the summer temperatures can build up sufficient pressure to burst hose (and see-gage glasses), a vent is provided in the form of a small relief valve (1) inside the main body of the control valve (See Figure 43b) or Delrin valve as shown in Figure 42 above. Through this valve any excess pressures in any part of the system above the air eliminator can escape through orifices (2) and (3) back into the eliminator where there is ample room to handle the expanded liquid.
Figure 43b
Removing and Cleaning Expansion Relief Valve
Bronze
It seldom should be necessary to remove the small expansion relief valve (1). See Figure 43b above. However, a possible accumulation of foreign matter could interfere with positive seating and result in gasoline dropping down out of the see-gage, leaving it only partially filled and cause the computer to jump when the pump is started. If such is the case, the relief valve (1) can be taken out for cleaning or replacement by removing the screw and spring at the end of the control valve body. The relief valve can be pushed out by inserting a stiff wire from the opposite end at point A. The small composition disc seat may be removed and turned over for longer life.
NOTE: This disc is interchangeable with discs in Bennett siphon and suspension valve No. E-1140 and in submerged pump check valve No. 70-N-1000
Delrin
Use any tire valve cap to remove the Dill tire valve for cleaning or replacement. Replace with Dill brand only. See Figure 42 .
While the rotor and shaft assembly had remained the same, the method of sealing changed during the production of the Type 40 pumping unit. The original production utilized a rotary seal as shown in Figure 44. Later production, starting with the 3000 Series, used the lip seal method as shown in Figure 45.
Figure 44 - Rotor Seal
NOTE: Parts are no longer available for units with the rotary seal. In order to repair units with rotary seals, order KR 162-01. KR-162 contains the following:
1. Rotor cover plate H-352201
2. Inner seal A247014
3. Lip seal A323702
4. Seal retainer H352101
5. Screw (3 ea) A099101
How to Install the Lip Seal
Remove the belt, pulley and shaft key. Remove the three screws that hold the seal retainer. Carefully pry the old seal from the recess in the cover plate--do not scratch the shaft. With a small plastic expander tool (furnished with new seal), slip the new seal over the shaft which has been wiped clean. Remove the tool. Reinstall the seal retainer screws, key, pulley, and belt.
Figure 45 - Lip Seal
How to Service Rotor Assembly
1. Remove the belt and pump pulley, being careful not to lose the shaft key.
2. Remove five cap screws, the cover plate ring, and gasket. Be sure to mark the position of the rotor cover (1) so it is returned to the same position during reassembly. See Figure 46.
Figure 46 - Rotor Assembly
3. The rotor cover is a close fit. If it does not loosen by hand, tap lightly with a ball hammer on the hex-shaped hub at various points until free.
4. Pull the assembly out slowly and catch the blades (2) with a free hand.
The Bennett designed rotor contributes to quiet operation and high vacuum. The blades are fitted into their slots with .002 inch clearance. The rotor, turning about 615 R.P.M. with .001 inch clearance on both faces and at the top, causes the blades to continually contact the surface of the pump body bore by centrifugal action. The blades must slide freely back and forth in their slots. If dirt, corrosion or gum forms, the result will be that one or more of the blades will bind. This causes a distinct throb or vibration that can be felt at the nozzle while delivery is being made.
Clean the blades with emery paper to remove foreign matter only. Run a fine, flat file through each slot, removing only the foreign matter.
CAUTION: Be careful not to file away metal that will result in wider slots.
Before reinstalling, wash the blades and rotor in a solvent. Also, inspect and clean the holes (3) drilled in the bottom of each blade slot to give freedom from liquid blocking of the blade action.
NOTE: Click here to Consult the appropriate model Parts List for the Type 40 Pumping Unit.