Do you need to know exactly the specific amount of chemicals that you must inject into a dosing process? The calibration columns verify the volume provided by a dosing pump. Today we talk about this type of instrument.
As specialists and manufacturers of flow measurement equipment, we carry out mechanical or electronical solutions creating new products, updating existing ones and adapting them if necessary customized to the needs of our customers in their day-to-day. One of these devices is the calibration columns.
Calibration columns, also called calibration cylinders, are tubes with a graduated volume scale that are widely used in any chemical dosing system.
It is a straight cylindrical tube and to determine its size it is necessary to know the volume that customer needs to measure.
What are they used for?
The calibration columns are instruments that are used to corroborate the accuracy of the volume offered by a pump and let you know what its operating status is, if it is mechanically adjusted or if it needs maintenance of some kind.
One of the most common uses is to determine the amount of chemicals that we are going to inject into the dosing process or any other liquid that we want to dose, in a simple and exact way. They ensure that the system pump doses a specific amount of liquid, verified by this type of graduated cylinders.
It is not a dosing device but calibration equipment, that is, to check that the correct amount of liquid is being dosed to the process.
And how are they used?
They are usually installed in the suction or discharge line of the dosing pump and the tank where the chemical product we want to dose is located although, in reality, it can go anywhere in the process depending on what it is going to be used for.
For example, it can be installed just before the mixing tank. You close the valve of the line and open the valve of the cylinder observing the level variation that takes place in it during a certain time. When the desired volume is reached you close again the valve, confirming that the volume to be added is correct according to the adjustment of the dosing pump (See figure 1).
The ideal is to calibrate the pump according to the actual conditions to ensure an addition as accurate as possible.
Figure 1
For the manufacturer, it is important to know the pressure and temperature data of the liquid to select the thickness/height of the glass tube of the calibration column at the time of manufacturing. In Tecfluid, these are the maximum parameters:
Maximum temperature 80ºC SS / PP / PVDF
Maximum temperature 70ºC PVC-C
Maximum temperature 60ºC PVC
Maximum pressure: 5 bar
Manufacturing materials
Given the type of products with which they are used, the calibration columns are made of corrosion-resistant materials. The material will depend on the chemical compatibility of the liquid of the process that we are going to dose.
At Tecfluid we can manufacture calibration columns in different materials, although the graduated tube is always made of borosilicate glass:
- PVC
- PVC-C
- PVDF
- PP
- AISI 316L
The materials of gaskets can be Viton ®, EPDM and NBR.
The borosilicate glass tube is marked or engraved with precise graduated scales allowing quick and clear checking of the fluid it contains. It will be interesting for you to watch this video if you want to know how is the process of laser engraving of the glass tubes scales.
Sizes and connections
The size of the calibration column will depend on the size of the pump that we are going to work with. To determine this, it is necessary to know the volume that needs to be measured.
In Tecfluid, we do not usually talk about “usual volumes”. We have supplied from 50 ml to 10000 ml depending on the customer’s needs.
We can also manufacture in different upper/lower connections:
-Solvent weld sockets or socket ends for welding
-BSP or NPT thread
-EN 1092-1 or ASME B16.5 flange
… but if you have any special requirements for size or connections that we do not indicate here, contact us, we can help you.
Other options
We have calibration columns with a protective frame, in bypass for large volumes, with dual scales in gallons and ml … and we study other specifications that may arise in an application for this type of equipment.
Calibration columns with
stainless steel protection frame
Calibration columns in bypass
Some advantages of using calibration columns
- High reliability
- Reduced cost
- Direct reading
Some disadvantages of using them in front of other systems
- Do not allow continuous measurements
- We are limited in the capacity of the instrument
- Pressure and temperature limitation
These restrictions can be saved by using other volume measurement systems that we have in Tecfluid, such as the TM series turbine type flowmeters, one of the most used in the process industry, or the oscillating piston flowmeters COVOL series, a type of positive displacement flowmeter also called volumetric meter.
Technical drawings of different types of calibration columns developed by our R&D department
Do you know how our R&D department works? What does it do? How is it organized? This is explained to us by the R&D head in Tecfluid in this interview.
So, if you need a calibration column, contact us. We help you to define what you really need.