Portable mixers don’t usually get the credit they deserve, but this technology plays a pivotal role in critical industrial liquid-handling applications. Like pumps, portable mixers are an essential technology that can provide operators with several years of service if properly designed and engineered.
With any piece of industrial equipment, portable mixers are most efficient, effective and reliable when the proper model and style is used for a particular mixing or blending task. That’s why it’s imperative to consider several operational variables when specifying small portable mixers.
Neptune has a full range of portable mixers, which are ideally suited for blending liquids, suspending or dissolving solids, dispersing immiscible liquids and small amounts of gases in liquids. Through Neptune’s Mixer Selection Guide, the best small portable mixers can be identified for a particular task. Several elements should be considered when choosing a small mixer:
- Size of the batch: Small portable mixers are best used for batch sizes up to 100 gallons. Larger sizes, 200 gallons or higher, become too cumbersome and problematic for small mixers, which don’t have the power to effectively mix that kind of volume. Compatible small batch mixers from Neptune include its A and B Series, the BN Series, the BC and BF Series and L Series.
- Viscosity of the components: Similar to the batch size, the viscosity of the components is another parameter that must be considered for small mixers. A viscosity CPS of less than 500 is ideal for small mixers, such as the BN Series, which is the premier line of small direct drive mixers for mixing small batches of low viscosity fluids. The JD Series can also be used at the pinnacle of the batch and viscosity threshold for small mixers, which would be a batch size of 100 gallons and a viscosity at or near 500.
- Final products: The final mixed products are another factor when determining if a small or larger mixer is needed for the job. If the final mixed product does not have a high viscosity or a large volume of product, then a small mixer will handle it effectively.
The information provided in the Neptune Mixer Selection Guide is based on an approximate mix/blend time of two liquids for 30 minutes, with both liquids already in the tank. Mixing times will be shorter if one liquid is added to a second liquid while the mixer is operating. Powders should always be added while the mixer is running. The guide also applies to the suspension of solids with settling velocities of less than one foot (304.8 mm) per min.
For more rapid or vigorous mixing, use a mixer one or two sizes larger. Dual propellers are recommended for tanks 1,000 gallons (3,785.4 L) and larger at viscosities of 1,000 cP and higher.
In most applications involving small mixing tanks of 1,000 gallons (3,785.4 L) or less, the mixer is clamped to the side of the tank. Optimum mixing will be achieved when the mixer is angled from the tank wall, either off-center or on-center. Improperly mounting a portable mixer will greatly lessen mixing efficiency, cause vibration and could possibly damage the mixer.
Larger size tanks may require that a mixer be mounted directly in the center of the tank with the shaft vertical. When a mixer is used in this arrangement, baffles are recommended to prevent the contents of the tank from turning in the direction of the mix.
Baffling will avoid vortexing and allow mixing to be as thorough as possible. Neptune suggests that four baffles be used, located 90° apart and sized approximately 1/12 of the tank diameter. The baffle should not fully extend to the bottom of the tank and a gap should be provided between the baffle and the tank wall.
Portable mixers have an essential role in industrial liquid-handling applications, even if they don’t get the attention they deserve. Even the smaller mixers have their place, especially when selected for the proper mixing application.