Mixer Basics Step 8: Mounts and StandsPosted on September 23, 2014 by Stephen Pierce

Once you have your impeller, motor, and shaft youll need to mount the mixer to the container or set up a stand where you can lower the mixer in and out of different containers.With mounted mixers, you can mount the mixer to different containers and then move it to other containers as necessary. This might be helpful if you have a lot of containers that are really heavy and you dont want to move them.You can mount mixers to different containers using drums mounts, bung mounts, tote mounts, clamp mounts, flange mounts, plate mounts, and pail mounts. The easiest way to understand how they work is to look at them.

Drum Lid MountThis is a drum lid mount for a 55 gallon drum. The mixer is attached to the plate and you set the plate on top of the open drum.

Bung MountThis is a bung mount mixer. For this type of mixer you leave the lid on your 55 gallon drum or other container. The folding propellors used for a bung mount mixer fold up to go through the bung hole and then unfold once the mixer is started.

Tote MountThis is a tote bracket mounted mixer. The bracket you see expands and then clamps onto the outer edges of the container you are mixing in.

Clamp MountThis is a clamp mount mixer. It simply clamps on to the side of the container using a vice.

Flange MountThis is a flange mount. For those of you who have large tanks, you can attach this flange mount directly to the flange. This kind of mount usually requires a seal between the mount and the tank.

Plate MountThis is a plate mount mixer. Usually, this kind of mount is bolted to two c-channels. However, it can attach directly to anything that accommodates the plate.

Pail MountFinally, we have the pail mount mixer. The pail mount can attach to any five gallon pail.If the containers you are mixing in are mobile, then it might be easier to bring the containers to the mixer rather than have to lug the mixer all over the place. In that case we have different stands you can put the mixer on. We have airlifts, electric lifts, winch lifts, and manual lifts. The name of the lift describes the power that is used to operate the lift the mixer is on. You simply set your container on the stand and drop the mixer down into it using the lift.Now that you know what kind of impeller, motor, shaft, and stand you need, you have everything you need to order a mixer! Or if you still feel a little nervous, you can call one of sales engineers and they can answer any of the other questions that you might have. ResourcesMixer Basics Step 7: The ShaftPosted on September 23, 2014 by Stephen Pierce

When you are buying your mixer, youll most likely need to buy a shaft. The shaft is simply the piece of material that connects the motor to the impeller. The shaft can vary by diameter and length. The diameter of your shaft depends on the amount of torque required for mixing and the length depends on the size of the impeller.The more viscous your mixture is, the more torque your impeller needs. The more torque your impeller needs, the thicker your shaft needs to be. As the motor twists the shaft, the motors torque is transferred into the shaft. The shaft is then supposed to transfer the torque to the impeller. However, if the blade uses more torque than the shaft can transfer, then the shaft will vibrate and might possibly break. It would be like trying to turn a plastic spoon stuck in a mound of frozen ice cream. If the ice cream doesnt give, the spoon will break.

Plastic spoons and rock hard ice cream dont mix.To get the right diameter for your shaft, just solve this equation for d.

D is the diameter. M is the bending moment of the shaft. Tq is the torqe, and sigma is the tensile or shear stress.If that equation intimidates you like it does me, then you can call one of our engineers and they just tell you the right shaft size.The length of your shaft depends on the size of the mixing blade. If the shaft is too short, you can cause vortexing. Vortexing is when the mixture starts spinning so fast that the surface of mixture gets below the impeller. Its like creating a liquid tornado in your mixing vessel. Once the tornado touches the blade, youve got problems. It would mean that you could see the blade while it is spinning in your mixture. For most mixtures, this creates problems because when you can see the blade it means you are mixing air into your mixture.

Causing a vortex while mixing will unfortunately blend air into your mixture.In order to avoid vortexing you need to have good coverage. Coverage is how far the impeller is underneath the surface of the mixture. We usually recommend that the blade be underneath the surface of the mixture by two times the length of the diameter of the impeller. So if the impeller is one foot wide, then you want the blade to be two or more feet underneath the surface of the mixture. If you need your impeller to be at least two feet underneath the surface of the mixture, then your shaft will need to be longer than two feet in order to accommodate the motor, the blade, the coverage and the freeboard (freeboard is the distance from the surface of the mixture to the top of the container).Once youve figured out what kind of shaft you need, you should consider what kind of mount or stand you need. ResourcesMixer Basics Step 6: Power SupplyPosted on September 23, 2014 by Stephen Pierce

At Mixer Direct, we sell two basic kinds of motors. The first motor is powered by alternating current electricity. The second kind is powered by compressed air. Though we do sell other kinds of motors, these are the two basic kinds that we sell.If you are buying an electric motor, there might come a point in the purchasing process where when you find yourself asking: Should I buy a single phase powered motor or a three phase powered motor? Then, if youre like me, you find yourself asking, Whats a phase?The phase here has to do with the electrical power that you have available at your building. Since electricity travels in waves, the easiest way to think about it is to think of waves at the ocean.Imagine if you could harness the power of the ocean wave every time it hit the sand. Single phase would be like having a wave hit the sand every three seconds. Now imagine that as the wave recedes back into the ocean, you have no power.

Single phase power would only have one wave over a period of three seconds.Three phase electricity would be like having three waves hit the sand in three seconds. The wave would hit the sand, but before it could recede another wave would be crashing on top of it. With three phase power, you would have constant energy, whereas with single phase power you would have points of time with no power.

Three phase power would have three waves of power over a period of three seconds.Most homes and residences have single-phase power. Many, but not all, industrial buildings have three-phase power. Single phase is less powerful and less efficient because the energy supply is not constant, but it is cheaper to install. Three phase is more powerful and more efficient because the energy supply is constant, but it is more expensive to install.So how can you tell what kind of power you have? Well, the first thing is to look at the kind of plugs you have. If you have the standard, three-prong plug outlet then you have single-phase power (that is for Americans. If you live somewhere besides the States, your outlets will look different). If you have plugs that dont look like standard outlets, then you might have three-phase (three phase comes in 240 or 480 volts). I say, might because a strange looking outlet does not automatically mean you have a three phase power supply. If you take a look at what you have and you still feel uncomfortable making the call, call your power company and they can let you know what kind of power you have running to your building.

Three phase outlets are found in many industrial building while single phase outlets are found in most homes and offices.Now, if you have industrial powered compressed air, you might consider an air powered motor. One of the biggest reasons you might consider an air powered motor is if you need your motor to be explosion proof. Another reason you might want an air-powered motor is if you are trying to conserve space since these motors are generally smaller than electric motors.Unfortunately, air powered motors have some drawbacks. First, they cannot create much power. Most air motors are 3 horsepower or less. Second, you need industrial rated compressed air to power these motors. The air compressor that you can buy at your local home improvement store wont power the motor properly. Finally, air motors air usually noisy and inefficient. However, even though these motors have these negative properties, they can be great for mixing paint, gas, or other combustible materials.Once you know your needed motor power and power supply, you can start looking at what kind of shaft youll need. ResourcesMixer Basics Step 5: The MotorPosted on September 23, 2014 by Stephen Pierce

When we talk motors, it is easy to think bigger is better. However, thats not always true, especially when you dont want to put more money into the mixer than you need to.When thinking about what kind of motor you need, you need to consider your shear and flow needs (shear meaning breaking down the chemicals in your mixture and flow meaning the rate at which the mixture moves about the container). Shear and flow are inversely related, so if you decrease your shear, you will increase your flow.

If you want shear, you are going to want speed. As the blade spins quickly, the energy from the blade is transferred into the mixture and breaks down the chemical bonds of the elements in the mixture. At the same time you need to be aware of the size of your mixing impeller. To get a large impeller to spin at the same speed as a small impeller, youll need a lot more power. For example, to turn a 5 inch impeller in water at 1750 RPMs, youd need a 0.5 HP motor. To turn a 10 inch impeller at the same speed would require a 13 HP motor. Thats an increase of 2600%.Flow takes less power to achieve than shear. Flow increases exponentially with impeller size. For example if you have a 5HP motor turning a 5 inch impeller at 1000 RPMs, you would get a bulk fluid velocity of 6.7 feet per minute. If you keep the other variables the same and increase the impeller size to 10, you would get a bulk fluid velocity of 38 feet per minute. If you increase the blade size to fifteen you would get a bulk fluid velocity of 104.9.

You also need to consider the mechanics of the motor. We sell direct drive motors and geared motors. A direct drive motor has no gears and grips the shaft going down into your mixture directly. All the power of the motor is then transferred as directly as possible into the mixture which is better for speed and shear. A geared motor has gears. Those gears are used to create torque which is better for turning a large blade to achieve a high flow.Once you have decided what kind of horsepower you are going to need from your motor, you can start looking at what kind of power supply youll want to use to run your mixer. ResourcesMixer Basics Step 4: Tank to Impeller RatiosPosted on September 23, 2014 by Stephen Pierce

If you are building a mixing system, one of the things that you have to consider is the size of the tank compared to the size of the impeller. We look at the size of the tank as compared to the size of the mixer using a D/T ratio where the D stands for the diameter of the mixing blade and the T stands for the width of the tank.In a perfect world, you would want your impellers diameter to be one-third of your tanks diamter. For example, if you had a 24-inch wide tank, you would want a blade 8 inches in diameter. Unfortunately, we dont live in a perfect world, and the ratio is not always a perfect 1/3. That means we will usually shoot to have D/T ratio between 1/5 to 3/5.

In a perfect world, your tank and impeller ratios would be like this.If the ratio is less than 1/5, then it most likely means your blade is too small for your tank. The blade wont be able to generate enough flow in order to mix the elements in the tank thoroughly.

A impeller that is too small for your tank wont create enough flow to mix the elements in your tank.If your ratio is more than 3/5, then it most likely means the blade is too big for the container. A blade that is too big might keep the top half of the mixture from interacting with the bottom half of the mixture because the material might not be able to move freely between the wall of the tank and the blade. However, the exact D/T ratio that youll need for your mixing will depend on your specific project.

An impeller that is too big will cut off the flow to the top of the tank.In terms of the height of the mixing blade in your tank, the optimal height is to have the blade 1/3 the length of the tank off the bottom of the tank. For example, if you had a tank that was 24 inches tall, youd want your blade to be 8 inches off the bottom of the tank.If the blade gets too low in the tank, then you may find that there are portions of your mixture directly beneath the blade that did not get mixed well.

A shaft that is too long will trap your mixture beneath the impeller leaving it unmixed.If the blade gets too high in the tank, you could cause vortexing (read more about vortexing in this article on shaft length). Again, we dont live in a perfect world and sometimes the blade height will be higher or lower than one-third the length of the tank. However, there are other ways to make sure you combat poor mixing mechanics.

An impeller on a short shaft can pull the surface of the liquid below the impeller and mix air into the mixture in a process known as vortexing.For example, you can combat vortexing in your tank by having baffles installed. Baffles are simply long pieces of material installed inside the tank that the fluid in the tank must move around. This movement around the baffles breaks up the flow mixture and keeps it from spinning itself into a vortex.Once you have your blade type and size, youll want to consider what kind of motor youll need. ResourcesMixer Basics Step 3: ImpellersPosted on September 23, 2014 by Stephen Pierce

Before we talk about impellers, we have to get some of the nomenclature straightened out. There are impellers, propellers, blades, foils, and a host of other names for the item that is actually spinning in the mixture. However, most people simply use the word impeller as a universal way of saying that little piece on the end of the shaft that spins around. With that being understood lets look at the different kinds of impellers and their flow patterns because, for the most part, flow pattern is determined by the blade.The first kind of impeller is called a straight-blade. As the name implies the blades are straight up and down. This kind of impeller pushes the mixture in your container straight out against the walls of your container giving you radial flow. Straight blades are great for intense mixing needs such as dispersion and emulsion, but they are not good for solid suspension.

Straight-Blade ImpellerThe next kind of blade, and perhaps the most common, is called pitched which is another way of saying, angled. The individual blades of the impeller are usually angled at 45 degrees. The angle of the blades forces the mixture downward creating axial flow. Pitched impellers are good general-purpose impellers.

Pitched ImpellerThe next kind of impeller is called a hydrofoil. This kind of impeller has blades with the greatest amount of angle. They are almost parallel with the bottom of the tank. When they spin they force most of the mixture downward. This feature makes hydrofoils great for those who have axial flow and solid suspension needs. However, the hydrofoils steep angle limits their effectiveness for dispersion and high viscosity mixing.

HydrofoilThe last kind of impeller is called a dispersion blade. Dispersion blades are meant for just that: dispersion. That means they break down the mixture well but they dont create a whole lot of flow. The flow they do create is radial, but that flow is minimal.

Dispersion BladeOnce you know what kind of impeller you want for your mixer, youll want to consider how big that impeller needs to be. ResourcesMixer Basics Step 2: Flow PatternsPosted on September 23, 2014 by Stephen Pierce

Three basic flow patterns exist: rotational flow, an axial flow, or a radial flow.Rotational flow is usually avoided or limited. With rotational flow, the mixture moves around the shaft of the mixer without really getting mixed. If you dropped a ball into a tank mixing water with a rotational flow, the ball would essentially orbit the shaft of the mixer without moving up or down in the container. Rotational flow spins liquids around the without mixing them. However, rotational flow can break the surface tension of the mixture by creating a vortex. This can be used helpful for adding other liquids and solids into the mixture.

Rotational flowAxial flow is the most efficient flow for bulk blending. With axial flow, the individual blades on the propeller are angled downward. When the blade spins, it pushes the mixture down towards the bottom of the tank. As the mixture hits the bottom of the tank, it bounces off and moves towards the sides of the tank. The continued force of the moving blade moves the mixture up the sides of the tank, and then begins to recirculate as the spinning blade pulls in the mixture from above. This type of flow provides great mixing for a wide range of conditions. Also, if you are looking for a way to suspend solids in a liquid mixture (think of suspending sugar in hot tea in order to give it time to melt) this is the kind of flow youll want.

Axial flowFinally, radial flow pushes the mixture out towards the side of the tank. Part of the mixture hits the side of the tank and moves downward, while the other part hits the side of the tank and moves upward. Radial flow mixing is great for intense mixing needs like when you need to break down the molecular bonds of the items that you are mixing. Also, radial flow generally has a slower blending time than axial flow.

Radial flow

Once you know what kind of flow you want, youll want to get the right impeller type in order to achieve that flow. ResourcesMixer Basics Step 1: Flow and ShearPosted on September 23, 2014 by Stephen Pierce

Youve decided you need a mixer. Thats great, but where to start? You have impellers, shafts, motors, and mounts to consider. At Mixer Direct, we usually suggest you start by looking at your flow and shear needs.Shear is essentially the rate at which your product will be broken into smaller particles. The more speed and power you have, the more it breaks down the particles. The more broken down the particles, the easier it is for them to mix.Flow is the rate at which your product will moves around the container. Typically, flow and shear are inversely related.

Consider it this way: when mixing you have two choices of where to put your power. You can put power into spinning the impeller extremely fast which breaks down the molecular bonds of of your mixture near the impeller, but this fast movement at the center of the container does not move the product around the container very well. Alternately, you can put your power into moving your material around the container with a large blade which spins slower. The slower blade means the mixer has less power to break down the bonds between particles.You would want a mixer with high-shear and low flow when mixing oil and water. You want to disperse (i.e. breakdown into really small pieces) the oil and water. To break the particles of the water and oil down small enough so they will blend together requires high-shear.Medium-shear with medium flow is usually used for thick, viscous mixtures like pancake batter. You need power to break down the items that you are mixing but you cant use a lot of speed because the mixture is so thick. At the time you have to move your mixture around the container to make sure all the pancake powder and water mix.Low-shear with high flow is usually used for watery, liquid mixtures like when you make sweet tea. The idea here is not that you need a lot of power or speed to break down the mixture, but rather you simply need movement in order to allow the chemical reaction to take place. For the example, when adding sugar to tea, you need to stir the mixture to keep the sugar from settling on the bottom. This solid suspension mixing is one type of low-shear, high flow mixing.

Partial Suspension

Off-bottom Suspension

Full SuspensionOnce you know what you shear and flow needs are, youll probably want to consider what kind of flow pattern youll want for your mixture.