There are two pumps that are commonly used with biodiesel processors. The NT Clearwater Pump has a long history of reliability when used for making biodiesel. The less expensive Harbor Freight pump is somewhat less reliable. For better or worse, homebrewing seems to be wedded to these pumps. You find them on nearly every set of processor plans and nearly every homebrew processor kit.

They have two strong advantages of being inexpensive and extremely good at mixing. In fact they are so inexpensive that the pump industry classifies them as “disposable pumps.” If we had to follow the industrial codes and regulations we would be spending over $1,000 for an “approved” pump to make biodiesel.

They are called “regenerative turbine pumps” and are a variant of the common centrifugal pump. The common centrifugal pump feeds the input into the center of the pump. The liquid makes one pass through the blades and is output along the outer edge of the rotor blades. In the regenerative turbine pump, the liquid is fed to the edge of the pump and travels around the edge of the rotor blades in a special groove to the output port. As it travels around the pump, it passes through the blades many thousands of times, each pass building up a little more pressure on the output port. The result is a very high shear mixing pump. The flow is so turbulent that any trash will quickly damage the pump through pitting if using anything other than cast iron for the pump housing. The pump was designed specifically to trade off flow for increased head pressure. These pumps can build up to about 40 or 50 psi on the output. The American versions are made with tighter tolerances and can typically build up over 250 psi.

Electrical Upgrades

The Harbor Freight pump uses a capacitor that is undersized, causing it to blow out easily. Neither pump has any thermal protection, meaning that if the pump locks up for whatever reason, it will over heat and possibly catch on fire.

The first thing to do when your capacitor blow out is to replace it with the right one. The stock capacitor is rated at 16 micro farads and 240V. Due to the way the motors are wired, the capacitor sees double the applied voltage, so under normal conditions 120 volts applied to the motor will apply 240 volts to the capacitor. Now if you add any kind of power fluctuation like a small spike, the capacitor is overloaded and blows out. What you need is a capacitor that is 300V and about 16-20 microfarads. The extra voltage in the rating gives the pump the ability to absorb those voltage spikes that would burn out the capacitor in the stock pump. They can be purchased at an electrical supply house for about half the price of a new pump. Be sure to tell them you want an AC capacitor. A DC capacitor would quickly burn out without ever starting your motor.

While were upgrading with a new capacitor, lets also add a little safety feature. The simplest is a 10 amp slow blow fuse wired inline. If some trash gets in the pump that locks it up or the pump is started with a defective capacitor, it will quickly draw 12-13 amps. A 10 amp slow blow fuse will protect against a locked rotor, but will not protect against thermal overloading. In higher quality pumps thermal protection units come standard, but we need to add something for this pump. To provide true thermal protection we need to look at options including a thermal snap-disc or a manual motor starter.

The manual motor starter is the best way to make the HF and NT pumps safe as it has thermal overload protection built into it and can be used as an on off switch. The Allen Bradley part number is 600-TAX4 and you will need a heater, part no P32, rated for 7.7 amps. These cost $30-$60 and are available at your local electrical supply house. They may not have the Allen Bradley items, but they will be able to use the Allen Bradley part numbers to cross reference to whatever brand they stock.

Leak Prevention

Whenever you see a picture of a Harbor Freight pump on a processor, you will almost always see a drip pan. They leak from several places. If you ever run them dry without oil in them, you will damage the seals and they will leak past the seal. You will notice the drip seems to be coming from between the pump and the motor. I don’t know of any fix or replacement seals so once it leaks there it will always leak there. They also leak past the threads on the in and out ports.

The input port has straight cut over sized threads. When you tighten a 1″ pipe in it, only a single thread is catching and tightening. After you run the pump a few times, the vibrations will loosen it up and it will leak. People have used lots of teflon tape, to seal it. Many have become frustrated with how it will loosen up and start leaking periodically and have resorted to JB Weld. Once you go there the pipe becomes part of the thread. I’ve heard of all kinds of fixes for this leak. JB Weld seems to be the most successful long term. Note that while the NT pump also has straight threads here, they are not oversized and people don’t seem to have the leaking problem we have with the HF pump.

The output port is not deep enough or relieved at the bottom like it should be. It’s like the cut off the end of the tap before cutting the threads. What happens is the first thread bottoms out in the bottom of the hole. Again we have the case where only one thread is holding the pipe in the port and after a few hours running starts leaking. We see this in the cutaway picture above of the blue pump and the black pipe. The best long term solution I’ve seen for this leak is to cut off the first three threads of the nipple you are screwing into the port. When you do that, the nipple is not long enough to bottom out and then will tighten up across all the threads at one time like it should. Note the NT pump has a proper relief at the bottom of the threads and will usually tighten without leaking.

The priming port is a screw on the top of the pump. beneath it is a rubber gasket of some sort that biodiesel/ methanol / wvo will melt. When it starts leaking, remove the goo that used to be the gasket and wrap the plug with teflon tape before tightening back in place. The NT pump uses a nitrile gasket that holds up much better.

One other mention about the HF pump. The fan shroud on the back of the motor can become misaligned during shipping and crush up against the fan. If it is, the motor will not work. The fan shroud should not be touching the fan, and the fan should be able to turn freely. The latest HF pumps dont seem to have as much trouble with this as they did in the past. The NT pump has the fan shroud bolted in place, so it’s not an issue with it.

The Classic Appleseed is a no welding required processor that is easy to assemble from locally acquired materials. It was made popular by Maria “Girl Mark” Alovert in her whirlwind of nationwide workshops. It took nearly four years to fine tune the original and come up with this layout. It’s the same layout used in the B100 Supply Kit. In this version the only part that may be difficult to find locally is the bimetallic thermometer and it can be found on the internet at most of the biodiesel equipment supply web sites. The plumbing should be made out of black pipe, but galvanized will do in a pinch. Brass ball valves are good, just make sure the ball on the inside is made out of metal. Some of the cheaper ones are metal plated plastic balls. While a used water heater will work, it’s a lot easier to start with a new one. You’ll spend at least a day cleaning out a used one and the fittings may not want to come out. If you look you may be able to find a scratch and dent or returned water heater that the hardware store may sell you at a discount. You want to get the cheapest electric water heater available in the size you want. The more expensive ones have electronic controls on them that would make wiring the water heater difficult. For processors made out of 40 gallon or smaller water heaters, I prefer the low-boy or short fat water heaters because mixing can be better in them. It’s easier to drain the glycerin more cleanly with less mixed bio/glycerin with a tall skinny water heater. When building your Appleseed Processor, you will want to remove both the dip tube in the cold water inlet and the anode rod. The dip tube is a plastic tube found under the nipple in the cold water inlet. Once the nipple is out, the dip tube will break loose by sticking a screwdriver down inside the dip tube and rocking the handle from side to side. Once it’s broken loose, just jam a finger down in the dip tube and pull it out. The anode rod is usually found on the top of the water heater under a plate and is usually labeled. So far all of them I’ve seen have been a 1-1/16″ hex. The same size found on a ford truck tire tool. Both the vent and the pressure relief valve on top need to be plumbed away from your workspace. The vent will during normal operation emit methanol vapors and you want them directed to where they can be dissipated without risk of poisoning people or animals. The stock TNP can be left in or replaced with a pipe plug. One note is that as the temperature rises near 200°F the valve will crack open and leak, so it will need to be plumbed like the vents, away from your workspace. You will also need to disable the upper heating element. More on that later.

Bill of Materials Item…Description………………….QTY….Notes A……3/4″ X 4″ pipe nipple………….3 B……3/4″ x 45 deg Elbow……………1 C……3/4″ x close nipple……………8 D……3/4″ x 2/4″ x 1/2″ TEE…………2…..Note 2 E……1/2″ hose barb………………..3 F……1/2″ ball valve……………….2 G……1/2″ close nipple……………..3 H……1/2″ street elbow……………..1 I……1/2″ swing check valve…………1 J……3/4″ x 1/2″ bushing……………1 K……3/4″ cross……………………1 L……3/4″ ball valve……………….4 M……3/4″ hose barb………………..5 N……3/4″ union……………………1 O……1″ x 3/4″ bushing……………..1 P……pump…………………………1…..Note 1 Q……1″ close nipple……………….1 R……1″ x 3/4″ x 3/4″ TEE………….1…..Note 2 S……3/4″ braid reinforced PVC tubing 6ft…..note 4 T……12 gauge power cord…………..6ft U……thermometer………………….1…..note 3 V……3/4″ x 1/2″ x 3/4″ TEE………..1…..Note 2 W……1/2″ ID clear PVC tubing………10 ft…..note 4 X……3/4″ pipe plug………………….1 Y……1/2″ elbow……………………..1 Z……3/4″ x 16″ pipe nipple…………1 AA…..3/4″ elbow………………………2 AB…..1/2″ x 12″ pipe nipple…………1 AC…..3/4″ x 12″ pipe nipple…………1 AD…..30psi relief valve……………1…..note 5

Note 1) Available from Northern Tools (Item# 109955).

Note 2) TEEs are specified as end x end x middle so a 3/4″ x 3/4″ x 1/2″ TEE would have the 1/2″ threads in the middle and the 3/4″ threads on the ends.

Note 3) This thermometer is available from B100 Supply. It can sometimes be found used for BBQ grills as well. The earlier versions used an automotive mechanical water temperature gauge.

Note 4) If you purchase from the big box hardware store, all that will be available will be PVC tubing. PVC tubing is not compatible with biodiesel and will eventually degrade and fail. As soon as you notice the tubing start to degrade, replace it with either new tubing or steel plumbing.

Photo courtesy of www.biodieselcommunity.org

The Appleseed Biodiesel Processor is a water heater based processor made popular by Maria “Girl Mark” Alovert, through the internet and her nationwide workshop tours where she teaches making biodiesel using the Appleseed design. Her course material eventually turned into an ezine that Girl Mark publishes herself. Her book Biodiesel Homebrew Guide is available through her web site www.localb100.com/book.html.

Like so many of the world’s greatest inventions, Girl Mark drew her original design on the back of a napkin at a coffeehouse as a project for an East Bay (California) Biodiesel Internship she was teaching with Jennifer Radtke of Biofuel Oasis and Backyardbiodiesel.org. While assembling the first water heater-based processor as part of the course, Girl Mark and a number of the students, including Amber Crowley, worked out some of the kinks in the design. The original criteria for the design included:

1. No welding required
2. Readily available parts
3. Improved safety

After the course was over Girl Mark led the effort to develop the design with the aid of the Internet. Using a number of forum boards for communication, Girl Mark was able to engage a large number of volunteers to test out and improve on the design.

The result is the biodiesel processor that is now known as the Appleseed, which has been adopted as a safe, reliable standard. As the safest and lowest cost design available, it is the processor design of choice for thousands of biodiesel enthusiasts in the US and other countries. It can be built in a day and, if based on a 40 gallon water heater, typically makes 25 gallons at a time. If relying heavily on used parts, one can be built for under $400. If using all new parts it can cost upwards of $800. There are several internet stores selling biodiesel kits and turnkey processors based on the appleseed design for prices ranging from $600 to $6,000

The design has continued to develop over the years and numerous improvements and upgrades can be found on the infopop forum, including a design which flips the water heater upside down. In our next post on the Appleseed we will cover an upgraded Appleseed Biodiesel Processor in more detail.

One issue I have with the Appleseed biodiesel processor is that you have to add the methoxide slowly or quality will suffer. Since it does not mix inside the tank, we have to make sure the methoxide is evenly distributed through out the tank. To do that we add the methoxide slowly. How slowly depends on how fast you can turn over the oil in the tank. The typical pump used on an Appleseed is either the Harbor Freight or Northern Tool Clear Water Pump. These pumps will flow hot oil at about 7.5 gallons per minute. That means for a 40 gallon water heater making 25 gallon batches, you will pump all the oil through the pump once every three minutes or so. We want to inject the methoxide over four passes. That gives us a ratio of 18:1 oil to methoxide when injecting. What we find out is that this 18:1 ratio holds no matter what size water heater you have. I started off talking about the problem being that we have to inject the methoxide slowly. Well to be correct the problem is that until now we have not had an inexpensive way to consistently inject the methoxide at the proper rate.

Having heard that there was a venturi available on the market that would give us our 18:1 ratio using the Northern Tool Clear Water Pump, we went on the search. It took a while but we found the Mazzei 584 Venturi Injector that was made of methanol and biodiesel resistant material with a maximum temperature rating of 200F. At least it worked by the books. We did a lot of testing on the venturi and found that it had a methoxide injection rate of 15:1. That’s not quite our ideal 18:1 but close enough for the job. It will load all the methoxide in about 3 and a half passes through the pump.

One of the nice things about the venturi was that it really pulled a serious vacuum. It maxed out my vacuum gauge with 29″ on the gauge. It had no difficulty pulling up the tubing three feet from the floor to the venturi. The venturi will load down the pump enough to slow the flow rate from 7.5 gpm down to 6 gpm when being used to draw methoxide. It loads it down when not in use as well. Not quite as much as when it’s in use, but enough that we want to look at using a bypass for mixing.

A bypass lets the biodiesel go around the venturi when it’s not in use. This eliminates the head pressure on the pump and increases the flow in the circulation line. It’s a simple device that with a ball valve and union being the main components. Open the ball valve when the venturi is not in use, and close it when you want to inject the methoxide.