Re: Blow Tank Level Measurement
There are several suppliers of Capacitance Type level probes which have been used very successfully in pressure tank applications.
Material temperature, dielectric constant, sticking characteristics, etc., all become factors to consider when making the right selection but the suppliers can readily help you given the information or a sample of your material.
Check out companies such as:
Ametek
Monitrol
Endress+Hauser
Regards ■
Re: Blow Tank Level Measurement
How about using load cells on the blow pot. They will be outside
at normal conditions and filling could be done on mass bases.
Just make sure the pot is empty at the end of the conveying cycle. ■
Re: Blow Tank Level Measurement
Also visit
www.vegacontrols.co.uk
for capacitive level switches
Happy New Year ■
Teus
Re: Blow Tank Level Measurement
Yep, load cell is one of options in my mind..but it is quite difficult to install load cell because we need to install the support first at the body of blow tank..Could someone give an example of the "safe" installation of load cell support on blow tank body ?
Rgds,
Bangun. ■
Re: Blow Tank Level Measurement
Mounting blow pots on load cells is same as mounting silos.
Load cells are mounted on the legs.A number of vendors
have safe mounting load cells you can try this link. They
have some good information on vessel / tanks weighing.
http://www.appliedweighing.co.uk/category.asp?catid=2
If you go ahead with weighing make sure to get a controller
which can compensates for "time of flight". ■
Re: Blow Tank Level Measurement
The blow tank must be cheched for whether it is full.
This is a volumetric measurement.
Load cells (force measuremet) are influenced by external forces (pipe connections, pressures at the inlet and or outlet, etc).
Also a variatition in the bulkdensity will influence the degree of filling when load cells are used.
BR ■
Teus
Re: Blow Tank Level Measurement
So, what is your opinion Teus ? Should I use load cell or level switch or any others options?
Rgds
Bangun ■
Re: Blow Tank Level Measurement
Dear Bangun,
Make a good description of your application.
Material, temperature, drawing of the blow tank with the level tester position, ambient temperature, required electrical output (solid state or potential free contact).
If you mention this information on the forum, may be one or more forum members have already the necessary experience and solutions.
Send this information to the various vendors of level detection equipment and ask for a quotation of their solution.
As you have level testers in operation, also describe the problems with those, so that the same mistake can not be made twice.
Using load cells would start a new learning process and probably would cost more.
Try a level tester as a first option.
best regards ■
Teus
Level Control In Pneumatic Filling
Dear Bangun
The usual method is to use capacitance probes. However they need to be able to detect the difference between the air/powder mixture and the powder itself to ensure the tank/silo is filled to maximum. Two common applications include wood chip and cement powder.
Other considerations will be length of probe and temperature of the product. Whether you want a stand alone probe or a separate probe and controller.
Probes can be mounted vertically or horizontally.
You are welcome to view the applications pages on capacitance at Hawker Electronics website. hawker-electronics.co.uk
Load cells are excellent if designed into the silo in its basic state. Retro fitting them can be problematic. ■
Re: Blow Tank Level Measurement
Hei all,
i found the contactless level switch from berthold..Anyone have experience using it?
this level switch work using gamma spread. But I still curious obout some matters:
1. Does it save for human/environment? because gamma have a nuclear radiation, is'nt?
2. Can it still detect when hot dust plug in the tank wall?
3. The blow tank is filled dust from hopper above it. Does the level switch affect when blowtank is filled?
maybe someone who has an experience using the contactless level measurement can share it?
rgds
bangun ■
Re: Blow Tank Level Measurement
Nucleonic level measurement is used extensively on high hazard plants for solids and liquid level measurements.
The good news is that they are extemely reliable, much more reliable than any other sort of level measurement I have found.
the bad news is that the safety aspects of handling the sources are not insignificant.
If you have other sources on site and have the systems in place to handle them safely then by all means consider them for this duty. If this will be your only use of radioactive material, avoid it like the plague.
My personal preference for conveying vessels is loadcells with a back up capacitance probe / tuning fork or whatever is most suitable for the poder being handled.
The load cells i have found are generally more relaible than the probe so act as the high level, the probe acts as high high and only comes into play if there is a problem with the weigh system or if the density is too low and you hit max on level befor max on weight. ■
Re: Blow Tank Level Measurement
I whole heartidly concur that load cells are the least problematic with as long as you have good flexible connectors at all the connection points of the pressure tank or they could cause inaccurate readings.
I've been there and done that and it isn't pretty!
Jack ■
Blow Tank level measurement
Dear experts,
my company used level switch in blow tank that used to convey high temperature dust in pneumatic convy system. That level switch is used for material filling process interlock. But, the problem is the reliability of level switch, just because of the "extreme condition" in the blow tank (now, the material filling use time base process, the PLC will open the inlet valve for 10 sec). Surely this is not effective methode, so i'm looking for the suitable level switch for that aim. Could someone tell me the type of level switch that suitable for that condition?
Thanks and
Best Regard,
Bangun
bangunprayogi@yahooo.com ■