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Hydraulic ram pump

How-to


By Tom Moates

Virginia



Here on our 20-acre off-grid homestead in the Blue Ridge Mountains of Virginia, there are solar panels on a manual tracker, a house with passive solar designing, and organic gardens, but it’s the “chu-chunking” ram pump that supplies our water from a spring in a valley which spellbinds visitors-every time. The simple machine rhythmically gushes water…then stops…then gushes…then stops. It’s hypnotic. It’s non-electric. And, it’s a superb example of how human technology can work with nature.

The ram pump described here is my own variation of an old VITA (Volunteers In Technical Assistance) design. This model is built from standard pipe fittings, and much of the building process is screwing it together. Total cost for the pump, even with getting the help of a local machinist for one of the valves, should run around $150.

Will a ram pump work for you?

Hydraulic ram pumps require a certain geography to work. You must have a collected water source on your property (like a dammed creek or boxed spring) with at least three vertical feet of drop to a pump site. Also, your water must flow a minimum of three gallons per minute to run this pump.

To give an example of how this pump can be configured, let’s look at my own installation. Here the spring varies from nothing to 15 gallons a minute depending on the time of year. The spring collection site is 25 vertical feet above the pump, the drive pipe is 125 feet long to the pump, and the delivery line is 400 feet long and rises 90 vertical feet. When there are six gallons of water available at the spring, I get about a gallon and a half a minute up top. That’s 2,160 gallons every 24 hours. The ram doesn’t send torrents of water gushing on demand the way an electric pump does; rather, it operates continually, sending a modest stream.

Generally storage is some type of cistern up hill with an overflow. Often rams are used to deliver water to a storage tank well above the desired destination and then the water is piped back down with gravity pressure taking care of the rest. Here, we store about 250 gallons and use a small Shur-Flo 12 volt diaphragm pump to pressurize our water line to the house. When the storage cistern is full the excess water coming from the ram runs out the overflow automatically irrigating various raised beds.

The beauty of the ram pump, for those who have the conditions to run one, is that there are only two moving parts to wear out. In this version, one is your basic over the counter 2″ check valve, and the other is a small rubber gasket that I like to cut from the sidewall of an old radial tire. There’s nothing to it-no wires, no motors, no pressure switches. Pumping water is a huge concern for any off-grid home, and this ram pump can save you the additional costs of extra photovoltaic panels, pump, wires, etc., which otherwise are necessary with electric pumps.

How does the hydraulic ram pump work?

The hydraulic ram uses the force of water running downhill through a pipe to then pump some of that water up hill to a site higher than the source.

Water enters the system by running from some source into an intake pipe. The water moves downhill through the pipe some distance, enters the pump, and then exits the pump (and therefore splashes out onto the ground) through an open “waste” valve. This produces a moving column of water inside the drive pipe.

Diagram courtesy of: the Complete Hydraulic Ram Manual
Diagram courtesy of: the Complete Hydraulic Ram Manual

By allowing the column of water to flow downhill freely through the waste valve, the kinetic energy of the moving water is prepared to work the pump.

The velocity of this water increases to a point that it overcomes the tension of the waste valve spring, and that valve slams closed. By abruptly stopping the flow of the column of water, a tremendous pressure is created. This pressure pushes forward through the street bend, through a one way “check” valve, and into an air compression chamber (the two foot capped pipe).

The water whooshes past the check valve (below the air chamber) with all its fury squishing the air in the compression chamber until the kinetic energy is converted to, and rests for an instant, as potential energy in the form of compressed air. Next, the compressed air pushes the water back out of the chamber with all the energy it has stored. Since the check valve is a one way valve, the water being forced backwards cannot return from whence it came; therefore this water is forced through the only place left to go…the exit gate valve and into the delivery pipe thus traveling up hill as far as the energy from the compression chamber will take it. Water continues to move as the ram cycles with the waste and check valves opening and closing and eventually reaches its uphill destination.

5:1 Ratio

There is an optimum configuration for the hydraulic ram’s set up. It is a 5 to 1 ratio, where the drive pipe length is five times longer than the vertical fall from the water source to the ram pump. Our installation is an example of this optimum situation: the drive pipe is 125 feet long and falls 25 vertical feet from the spring to the ram. Similarly, a 50 foot drive pipe dropping 10 vertical feet from source to ram would meet the 5:1 ratio.

A ram will run on either side of this ratio, but its efficiency suffers increasingly as you get away from it. So, try to create your overall system to accommodate this drive pipe scenario as best you can.

Building the ram

To build this average sized ram you will need:

Parts List Quantity
1″ gate valve (optional) 1
1″ nipple (only w/gate valve) 1
2″ x 1″ bushing 2
2″ tee 1
2″ street bend 1
2″ check valve 1
2″ nipple 2
2″ x 2″ x 1/2″ T 1
2″ threaded pipe 2′ long 1
2″ cap 1
1/2″ nipple 1
1/2″ gate valve (optional) 1
40″ of 1-1/2″ x 1/4″ strap 1
3/8″ x 4-1/2″ bolt w/nut 1
1/4″ x 3″ bolt w/2 nuts 1
3/8″ x 3″ bolt w/2 nuts 1
1/2″ copper pipe 3-3/4″ long 1
1/2″ x 1″ bolt w/1 nut 2
1/2″ lock washer 2
3/8″ flat washer 2
1/2″ flat washer 1
2″ small gauge copper or brasswire 1
roll Teflon tape 1

These materials should be available at any well stocked plumbing supply, hardware store, or farm supply. Avoid buying a check valve which is brass on brass. Water from a spring, creek, or river carries fine grit which chips away at the soft brass and will wear the check valve. It is better (and cheaper for that matter) to use a check valve which has a rubber or neoprene type diaphragm inside.

It’s really nice to have access to a heavy bench, vise, and several different sized pipe wrenches when assembling this pump-it will make the process a joy rather than an awkward, difficult battle.

Waste Valve

The waste valve is the only difficult aspect to building this pump. Joe Huffman, at Huffman Tool Company here locally, has worked with me to provide completed waste valve assemblies made from stainless steel, which screw right into place for folks who’d rather skip this part, which requires a bit of welding and machining (see resources info at end of article).

The first step to making the valve is to take one of the 2″ x 1″ bushings and machine the inside surface where the rubber washer/seal on the plunger will bear against it when in the closed position. This process can be done in one of two ways. The best is to chuck the bushing into a metal lathe and then have a sharp bit, which is held by another arm of the lathe, enter into the bushing where the uneven cast surface is machined away to a nice, perfectly flat surface. The other method is to use a flat grinding stone bit chucked in a drill press. Clamp the bushing upside down on the press table and then lower the spinning stone into the bushing and grind the rough cast surface until smooth.

Next, cut 4″ off the 40″ piece of 1-1/2″ x 1/4″ strap and braze or weld it in place on the top of the bushing close to, but not covering, the 1″ threaded hole. The galvanizing needs to be ground off the bushing to allow the brazing or welding to hold properly.

Drill two 1/2″ holes through the small strap on the bushing that correspond to two of the same size at one end of the 36″ of strap still remaining, so the two may be bolted together with a piece of rubber between them. The machinist does this drilling for me, and I have him elongate both holes half an inch long ways in the small, welded piece of strap, which allows for a slight adjustment when centering the plunger part of the waste valve.

Next, make a mark on the 36″ strap, 16″ from the end with the two 1/2″ holes and bend the strap around a 1-1/2″ pipe centering the mark in the bend to make the waste valve spring. Drill two 3/8″ holes corresponding to one another top and bottom of the spring right where it flattens out after the half circle bend to allow for the 3/8″ x 3″ bolt to pass through both holes. Add two nuts, one to adjust the tension of the spring and the other to act as a lock nut to keep the adjustment from moving during operation.

Two more holes must be drilled and then the hard part is over. Bolt the spring in place to the bushing with the two 1/2″ bolts finger tight, centered in the elongated adjustment bolt holes. Make a mark in the center of the strap exactly where it passes over the center of the 1″ in the bushing. Make another mark beyond the first towards the end of the spring directly over the far edge of the bushing. Now unbolt the spring from the bushing and drill a 1/4″ hole at the mark towards the end of the spring and a 3/8″ hole at the mark made directly over the bushing’s opening.

To complete the waste valve, cut a piece of rubber large enough to sandwich between the waste valve spring and the stud it bolts to on the bushing. Used tractor tire tube works well for this. Cut holes for the two 1/2″ bolts to pass through and then bolt the spring tightly in place using a lockwasher under each nut.

Take the 3/8″ bolt and place on it a 3/8″ flatwasher, then the 1/2″ flatwasher, then a piece of rubber cut into a 1-3/8″ outer diameter circle, and finally the length of copper pipe. Pass the fully loaded bolt through the machined bushing and then through the 3/8″ hole in the spring. On the top side of the spring add a lockwasher and a nut and tighten snugly the whole works.

I’ve experimented with several different types of rubber for the waste valve and the best for this abusive spot is soft radial tire sidewall. It can be cut with a sharp knife or leather scissors. Orient the soft outer side upwards so that it presses against the machined edge inside the bushing making the waste valve seal. This rubber makes a great seal and has nylon cord woven into it for durability. If your waste valve is properly aligned during operation so that it doesn’t rub on the side of the bushing, this rubber clack should last for several years.

It is imperative that this valve open and close in perfect alignment so that the rubber washer closes completely on the machined surface inside the bushing and that it not bump or rub the side of the bushing in any way as it opens and closes. Slightly bending the spring or bolt and/or adjusting the two pieces of spring at the elongated 1/2″ bolt holes works to tweak out a valve not perfectly aligned.

Finally add the 1/4″ bolt through the final hole left in the spring to make the opening depth of the waste valve adjustable. Be sure to place a nut on the bolt before sticking it through the hole, and then one after so that the carriage bolt may be adjusted up or down and then tightened in place.

The waste valve is now complete and needs only to be screwed into the system at a later point.

Snifter hole

When water and air are compressed together some of the air mixes with the water, and, because of this, in the ram pump bits of air leave the air chamber with each stroke. A small “snifter hole” is added below the air chamber to reintroduce gulps of air to the system constantly, thereby avoiding water-logging which will stop the ram.

To make the snifter, bore a 1/16″ hole through the center of the 2″ nipple that will go below the check valve. Once drilled, take some brass or copper wire, bend a right angle into one end, place it through the hole, and then bend another right angle into the other end. Voila, it’s pretty simple.

Putting it all together

The rest of the construction is very simple. Follow the diagram and screw each fitting into its proper place. Be sure to wrap all male threads with three wraps of plumber’s Teflon tape. When wrapping, make a point to go in a clockwise direction if you’re looking at the end of the pipe being taped so that the Teflon won’t unravel when you begin to screw it into its female partner.

Also, all joints should be screwed together tightly, but not tremendously so. Snug them up well, but keep in mind a pipe wrench large enough to grip 2″ fittings gives you more leverage than you need for tightening. Be extra careful when wrapping and tightening the cap at the top of the air compression chamber. This fitting can be screwed on extra tight; it is containing air rather than water and a leak will be difficult to detect.

A couple tips for screwing in the waste valve assembly-make sure you screw it in place before putting the street bend into that tee so that the long spring can turn full revolutions. Also, do not use the waste valve spring as a lever for tightening the waste valve into place. It is not a wrench and using it as one will bend the spring assembly and screw up all the delicate tweaking you’ve done to get the plunger centered in the bushing and the rubber clack closing perfectly. Use a pipe wrench and get a good, safe bite on the bushing to lever the waste valve around into a snug position on the tee.

Installation

When installing this pump there are only a few concerns to keep in mind. Drive this pump with a 1 inch drivepipe from start to finish. Rams should not be fed with drive pipes which throttle down (diminish in size). It’s important to have the intake screened off to keep animals and other stuff out of the drivepipe, and I like to add a 90 degree elbow at the inlet turned upwards to help keep sand out. Keep the drivepipe as straight as possible, especially the last third before the pump. The air chamber should remain perpendicular to the ground. The waste valve needs to be below the check valve (a situation that is nearly impossible to goof up with this design). Finally, nothing should come into contact with the waste valve spring-it should be suspended in free air, not touching the wall of a pump house for instance.

The flow from this pump is such that a 3/8 inch line could carry it. I use 1/2 inch black pipe because it’s more readily available, super cheap, and has more strength when handling than 3/8′s.

This 2″ pump is heavy enough for its size that it won’t jump around, but it is still essential to anchor it in some fashion to avoid the pump falling over or moving for whatever reason. Here on the homestead, I fastened the ram to a heavy oak board (which lays flat on the ground) using large conduit straps and tapcon screws. A friend up the road built a ram on this model and used a metal fence post driven into the ground at the back edge of the pump and then used muffler clamps to fasten the air chamber to the post. It works extremely well. This pump also can be anchored to a concrete slab if you provide anchor bolts in proper positions when poured. In some instances keeping the pump portable may be helpful; irrigating different areas of a farm at different times of the year, for example.

Getting it running and tuned up

Many times when a ram is connected for the first time it will begin to run on its own. They seem to love to run. But, here’s the whole rundown in order:

  1. Install drive pipe with gate valve at pump end, close gate valve so water isn’t running.
  2. Connect completed ram to end of drive pipe.
  3. Connect delivery line gate valve and delivery line which should be run to water destination and left unattached at that end so flow may be viewed once pump is running; delivery gate valve should be open.
  4. Hold up on waste valve spring so it remains closed and open drive pipe gate valve completely.
  5. Water should enter the pump, flow through and up the delivery line to the height of the source, and a small spray should come from the snifter hole.
  6. With the waste valve tension bolt completely loose and the carriage bolt stop completely up out of the way, let go of the waste valve spring which may or may not open on its own.
  7. For proper operation, the drive pipe will need to be completely full of water, so you may need tinkering time to get air worked out of the drive pipe.
  8. Slowly tighten the waste valve spring until the ram seems to operate smoothly; note that as the water gets pumped upwards in the delivery pipe the pressure changes on the pump and it will change speed and overall operation until the water is being delivered all the way to the end site at which time pump rhythm should become constant.
  9. Higher destinations require more pressure on the pump, so if it runs well but only delivers part way, increase waste valve spring tension.

If your source depletes and air is sucked into the drive pipe, the pump will stop running; adjust to a lighter spring tension and/or employ the carriage bolt stop by lowering it so it hits the top of the waste valve bushing preventing the waste valve from opening to its full capacity. Note: Very tiny adjustments can make huge differences in pump function, so make very light tweaks. Once running, the pump should cycle somewhere around 70 strokes per minute, but that’s not the complete gospel. You’ll get a feel for what your installation requires as you become familiar with it.

Resources


Huffman Tool Company, Joe Huffman, 540-745-3359, hufftool @aol.com.

Volunteers In Technical Assistance (VITA), Suite 710, 1600 Wilson Blvd., Arlington, VA 22209, 703-276-1800, vita@vita.org.

Headquarters and Western Service Center, Shurflo Pump Manufacturing Co. Inc., 12650 Westminster Ave., Santa Ana, CA 92706-2100; Main line: 714-554-7709; Toll free: 800-854-3218.

Eastern Distribution and Service Center, Shurflo East, 52748 Park Six Court, Elkhart, IN 46514-5427; Main line: 219-262-0478; Toll free: 800- 762-8094.
For more on Tom’s ram pumps, check out The Complete Hydraulic Ram Manual, illustrated by Chris Legg. $14.95 + $2.50 p&h to: Countryside Book Store, W11564 Hwy. 64, Withee, WI 54498; 800-551-5691.






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