Controlling pumps with your standard cable suspended float switch is honestly a pain in the neck. You’ll need at least two of them to get the job done, with a controller that handles all the logic. You have to tie them to some conduit to keep them from getting tangled. And the failure rate isn’t that great either.
Most maintenance technicians expect them to fail two or three years into service.
That’s why the Kari Float Switch is so awesome. It can have up to four switch points in a single float, built-in hysteresis to handle the logic, and doesn’t need to be secured to conduit since you usually only need one.
And they last a very long time. Some Kari Float Switches have been in service for over 20 years.
They’re also easy to use. A simple weight acts as the anchor point and can be adjusted to lengthen the distance between switch points. There’s not a lot more to it than that.
However, there are some nuances that are good to know about and will help you get the job done faster. Here are step by step instructions for float switch installation– for empty control and for fill control.
Let’s assume you have a KA-3H. This model has built-in hysteresis to control the emptying of a well or tank, with a high alarm – all in one float.
You should start with the lowest point because you never want the level to go below the required Net Positive Suction Head (NPSH) for your pump. Essentially, the NPSH is the suction pressure your pumps need to avoid cavitation and other problems.
In tanks and wells, liquid level equals pressure, so find that level and make sure you don’t go below it – for your pump’s sake.
Hint: Call us about NPSH if you have questions. We can help you calculate how much liquid level you’ll need to satisfy your pump’s requirements.
Float switch installation requires you to mount the device with some way of fixing the cable above the tank or well. There is a mounting bracket available for the Kari Float Switch that uses a snug wedge to fix the cable into place. This bracket can be attached to a wall or a rail using a simple bolt or screw.
The lowest allowable point is a good place to hang the bottom of your float when it’s vertical. We’ll refer to this point as ground zero. From here, the lowest switch for the KA-3H model will activate 9 inches above ground zero. This will happen at the “low” level.
If you choose a model with a low alarm (at the “low low” level), this switch point will activate at 5 inches above ground zero. The next lowest point (the “low” level) would activate at 9 inches above ground zero, or 4 inches above the low alarm.
The weight position determines how much space there is between the two higher points. The KA-3H, for example, uses both of these switch points to activate the pump at the “high” level and to activate a high alarm at the “high high” level.
The space between the “low” level and the “high” level is called the switching differential. Standard Kari switch points have a minimum differential of 10 inches, and maximum of 50 inches.
Moving the weight up and down on the cable will affect both the distance between the two high switches and the switching differential.
To give you a quick idea, the bottom of the weight will be about 6 inches or so from the bottom of the float, or ground zero, when the switching differential is 10 inches. At this weight position, the space between the two high switch points will be about 4 inches.
By contrast, the weight must be 35 inches from ground zero to get the maximum 50-inch switching differential. That would result in about 8 inches between the “high” and “high high” levels.
Once you’ve figured out the weight position and your switching levels, you’ll need to install float switch wiring to your waterproof enclosure. Make sure you seal the cable entrance with a cable gland.
For wiring instructions, refer to the user manual, or our new float switch wiring guide.
Each Kari Float Switch model will have a different number of conductors that need to be wired into different places. Typically, they share a common wire to complete the circuit. However, some of the models have isolated switch points that you can wire to a lower voltage alarm circuit, for example.
You’ll follow the same basic steps you did for empty control, but you have to reverse the way you determine your levels. Let’s use a KA-4L5E, which will control duplex pumps with a low alarm. It also has built-in hysteresis to control the on/off logic.
You need to prevent over-filling your tank, so start by choosing when you want the pump to turn off. For the KA-4L5E, this is the “high high” level.
The position of the weight will determine the distance of your highest point from ground zero, or the position of the bottom of the Kari Float Switch when it is hanging vertically.
So we’ll adjust our weight first, using the same method we learned in Step 3 for Empty Control. You’ll have to think backwards though:
How much space do you want between the switch points? How far does this push the float down?
Once you have figured out your switch points, use a clip or a mounting bracket to secure the cable above the well or tank, with the bottom of the float hanging at the exact position needed (ground zero).
Depending on your Kari model, wire up the cable to the appropriate terminals in your control panel box. Refer to our float switch wiring guide as mentioned above for additional help.
You won’t need to worry about hanging multiple float switches in the same well or tank, or about tying everything down so it doesn’t tangle. You can even skip the controller in backup pump control applications because of the built-in hysteresis.
There is nothing else like it on the market. Let us know how we can help with your float switch installation or selecting the correct device.
