The use of an Abanaki oil skimmer in a machine shop setting holds many benefits. Removing tramp oil from a machine tool coolant tank will create almost immediate aesthetic and health benefits by cutting down on smoke generated when hot cutting tool are bathed in oil-laden coolant.
When a machine with a circulating coolant system is shut down for the weekend, tramp oil (an unwanted contaminant)
Contrary to popular belief the common types of bacteria found in metalworking fluids do not cause dermatitis. However, if the skin is broken, bacteria that normally inhabit the skin may enter and cause infection. The presence of phosphates and carbonates that increase alkalinity in the coolant, however, can cause dermatitis. These impurities are found in the water being used in the coolant mix.
Separating tramp oil from the coolant will also help reduce disposal costs and allow better reclamation of cutting fluids. The cost of a coolant skimmer compared to disposing oil-laden coolant is an excellent investment. Disposing of coolant contaminated with tramp oil is more expensive than disposing of just the tramp oil separated from it. In some instances, companies may be able to reclaim the oil for use elsewhere, or sell it for recycling. Having oil-free coolant can also extend its usefulness and effectiveness, reduce maintenance expense, and cut down on coolant replacement costs.
Selecting a Skimmer Design.
When you begin researching oil skimmers, you will find a variety of separator designs. The most common types are the belt skimmers, disk skimmers, and tube skimmers. Each type of oil skimming has its advantages and disadvantages.
There are several factors that need to be considered when choosing the type of oil skimmer that best fits your particular application. These factors include water level fluctuation, water temperature, pH level, the use of rust inhibitors, the amount of oil to be skimmed, quality of the skimmed fluid, and cost. The use of rust inhibitors, high temperatures, and variable pH levels can affect the skimmers ability to pick up oil. Most skimmer manufacturers use a variety of materials for the skimming medium such as plastic, stainless steel, or polymer blends to match the solution in which they will be used.
While there are many oil skimming devices to choose from, two of the most important considerations are the performance and service life of the unit. Points of particular interest should include construction materials, motor design, and the type of warranty that is offered. Questions to ask are:
· Is the skimmer housing made of metal or plastic?
· Is the motor fan-cooled?
· Does the motor use needle bearings or bronze bearings?
· How long does the warranty last and what does it cover?
Most oil skimmers will perform as advertised when first purchased. How long they last may be another matter. Remember the old adage: "You get what you pay for."
Small Diameter Tube Skimmers. A tube skimmer is mounted to the side of a coolant tank and works by running an endless, small diameter tube (typically TYGON® material) over the surface of the coolant. The tube collects the oil and brings it back to the skimmer where it is removed and deposited into a disposal container.
Being able to mount this skimmer on the side of a machine coolant tank is this unit's biggest advantage, allowing it to work where vertical access into the fluid is not an option.
The biggest disadvantage is the minimal oil pick up rate (approximately one quart in 24 hours). An access hole must also be cut into the side of the coolant tank, which may cause coolant spillage. The cost of this unit is comparable to other oil skimmers.
Disk Skimmers. The disk skimmer is mounted to the top of the coolant tank and works by running a large diameter disk through the coolant surface. The disk itself is made of either plastic or stainless steel. As the disk passes through the coolant surface, oil is picked up and wiped off with a set of wiper blades as the disk passes between them.
Compared to some skimmers, a disk skimmer can have a slightly higher pick up rate (approximately one gallon per hour under optimum conditions). Another advantage is it tends to be at the lower end of the price scale.
A disadvantage of the disk skimmer is its requirement for greater operating space. For example, a 24" diameter wheel is required to reach a depth of approximately 12". The pickup rate drops dramatically if the water level does not cover at least half the surface area of the disk, making it unsuitable in tanks where the water level changes significantly. In addition, standard plastic disks can’t handle high operating temperatures (such as those in parts washers), and replacement disks made of stainless steel tend to be expensive.
Belt Skimmers. A belt skimmer can be mounted to either the top or edge of a coolant tank. It functions by running an endless belt (made of plastic, stainless steel or polymer material) through the fluid in the tank. The belt is held in the vertical position by means of a motorized head pulley and free-turning tail pulley. The belt travels through the surface of the coolant collecting the oil, and then passes through a pair of wiper blades where the oil is wiped off both sides of the belt.
Some of the advantages of using a belt skimmer include:
· A compact size that requires little operating space
· Good oil pick up rates (up to 2 gallons per hour, depending on belt width)
· Maintaining its maximum pickup rate with fluctuating coolant levels
· Typically, stainless steel belt material that makes it capable of operation in high temperatures without costly modifications.
· Cost comparable to other skimmer types.
When comparing a belt skimmer design to other types that have similar removal rates, it’s hard to find any disadvantages. Pricing and installation costs for a belt skimmer tend to comparable or better than the other types. In most cases, a belt skimmer design will be more robust than the other types.
In summary, to choose an appropriate oil skimmer, a user must consider the application in which it will be used. Factors including tank size, access to the coolant, oil removal rates, and operating environment must be assessed to choose the most appropriate skimmer.
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