1. Reservoirs Covered in Ch. 5 of Vickers Text
Jeremy Lawson
Jason Frentzel

2. Overview Functions of a reservoir Components of a reservoir
Types of Reservoirs
Modifications to Reservoirs
Sizing of Reservoirs
Heat Exchangers

3. Functions Holding system fluid Transfer of waste heat
Allows entrained air to rise and escape
Allows solid contamination to settle on bottom of tank

4. Components Baffle Plate Breather Assembly/ Filler Opening
Clean-out Plates
Oil Level Gage
Line Connections and Fittings

5. Baffle Plate
Used to prevent returning fluid from directly entering the pump inlet
Installed lengthwise through the center of the tank
This provides low velocity travel and allows for contamination to settle and for heat dissipation

6. Breather Assembly/Filler Opening
Accommodates the air exchange that results in a constant change in pressure
Must be large enough to handle the airflow requirements to maintain atmospheric pressure whether the tank is empty or full
Filler opening is part of the breather assembly
Filler has a removable screen to keep contaminates out of tank while filling

7. Clean-Out Plates Usually installed on both ends of tank
The plates should be easily removed and large enough to provide complete access when the interior of the reservoir is being cleaned or painted

8. Oil Level Gauge Used to check fluid level in reservoir
Either a sight glass or two port holes on the clean-out plate
These allow an easy visual check of fluid limits without the contamination caused by using a dipstick

9. Line Connections and Fittings
Most lines leading to the reservoir terminate below the oil level
Valve drain lines should extend two inches below the fluid level to prevent foaming
Pump return line should be cut at a 45 deg angle directed away from pump inlet to prevent the line from bottoming and cutting off flow

10. Types of Reservoirs JIC (Joint Industry Conference) L-Shaped
Overhead Stack
Vertically Mounted

11. JIC Reservoirs
A horizontal tank with extensions that hold it several inches off the floor
Permits air circulation and heat transfer from the bottom and sides
Tanks are usually as deep as they are wide and the length is about twice the width

12. JIC Reservoirs Made from 9 or 11 gauge pickled and oiled steel
Single bolt clean out plates at each end for cleaning access
Bottom is concave and has a drain plug at its lowest point
Filtered hydraulic fluid is pumped into the reservoir through a filler/breather cap.
A sight gauge is also installed with a thermometer

13. L-Shaped Vertical tank mounted on one side of a wide base
The other side of the base can hold the rest of the power unit, relief valve, and a heat exchanger
The fluid level in the tank is higher than the pump inlet which reduces the possibility of cavitations

14. L-Shaped
Pressure control and direction valves can be mounted to the side of the tank above the fluid level
If subplate valves are used then nearly all piping can be inserted into the reservoir to reduce losses due to leaks
The interior of the reservoir can be accessed through a hinged top even while operating
This design provides a large surface area for cooling and is also raised off the ground to promote air circulation

15. Overhead Stack
Consists of a standard horizontal tank on top of a modular rack with the rest of the power unit below the tank
This helps prevent cavitations especially for fluids with high density and low viscosity

16. Overhead Stack
For safety reasons, there should be no more than three stacking levels
This system allows for easier draining of the reservoir without the use of pumps
This system also conserves floor space by allowing two or more pump motor assemblies with controls to be incorporated in the rack mounting with a common reservoir

17. Vertically Mounted
Reservoir assemblies are frequently mounted vertically
Generally pump is enclosed inside of reservoir

18. Vertically Mounted Advantages are:
Reduced floor space
Increased cooling
Fluid acts as a dampener
Fluid creates a pressure head around the pump
Drive force stresses are reduced by gravity
Pump system is kept cleaner in the sealed reservoir
This has a drawback of having to remove the entire pump/motor assembly for maintenance

19. Modifications to Custom Reservoirs
Make sure the reservoir has ample cleanout openings that will be accessible in final position
Make sure walls and sides are strong enough to support equipment
Size should be at least 20% overcapacity of the system to provide a reserve for unexpected problems
Provide a means for filling, draining, and for a fluid level gauge

20. Sizing of Reservoirs Consider the following factors for sizing:
Fluid expansion caused by high temps.
Change in fluid levels during operation
Exposure of the tank interior to excess condensation
The amount of heat generated in the system

21. Sizing Reservoirs As a general rule of thumb:
Tank size (gallons)=
Pump gpm x2 or x3
In mobile or aerospace systems, space limitations sacrifice a large reservoir size

22. Heat Exchangers
Heaters
Water Coolers
Air Coolers

23. Heaters
Installed in the reservoir, below the fluid level, and close to the pump inlet
Used for low viscosity fluids

24. Water Coolers
Hydraulic fluid is circulated through the unit and around the tubes containing cool/hot water
Water flow requirements are usually equal to 1/4 and 1/3 of the system oil flow
The water is filtered to prevent the cooler from clogging

25. Air Coolers Air is used when water is not readily available
The fluid is pumped through tubes that are bonded to fins which transfer heat to the outside air
Air coolers are less efficient than water coolers and tend to be ineffective in areas of high ambient air temperatures

26. Homework
Chapter 5 in Vickers book
Problems 1,3,7,9

27. References
Eaton-Vickers Text, Industrial Hydraulics manual 4th edition 2001