Process connection for Hastelloy C DP transmitter

R

Thread Starter

Rahman

Hi All

I need a suggestion for one of my application where am working on DP transmitters for level monitoring of HCL and H2So4 tank (25000 liters).

I have a yokogawa/emerson make DP transmitter with wetted parts Hastelloy. C and process connection 1/2" threaded NPT. Storage tank MOC is MS.

My challenge is to select the compatible impulse tubing required when am connecting a DP transmitter to a HCL tank where the connectors of impulse tube are normally SS. Hence is there any way where i can use threaded DP transmitter for such application? Please advise.
 
When I did this at my last plant I purchased a PTFE lined armoured flexible hose with the mating connector in Hastelloy C.
 
The reason why you are having trouble is that you are using the wrong instrument for your application. When working with high heat or corosive products you dont want to use instruments that are in contact with these products. It is always best to make use of non contact level transmitters in applications like these, like a reflex radar or ultra sonic. Understandably most of these chemical vessels are closed and it is not always possible or practically possible to use non contact transmitters so the next type you should consider, that is also close to non-contact, is a DP transmitter with a chemical seal. The face of the seal should be made out of something that is acid resistant like PTFE, polypropylene or even PVC. This is also a very safe type of installation since the technician never comes into contact with the product, ever. Even with radars and ultra sonic the technician might still inhale some of the gas or get some of the acid on his skin during installation so that is why the DP with chemical seal is the best type of installation in your case.
If this is not possible due to position and type of tapping points on your vessel and you have to install the DP transmitter with the Hasteloy C insides, use PTFE, polypropylene or PVC tubing as impulse line. Just make sure you also look at the pressure rating if you have to go this unsafe way.
 
we started with ultrasonic and replaced it with a pressure transmitter. the ultrasonic gave all sorts of issues with HCL gasaing off in hot weather and the tank itself distorting in direct sunlight. the PT with Hastelloy C wetted parts gave no trouble over years of use.
 
A

Asok Kumar Hait

Hello,

Your problem is to select proper impulse tube material. You haven't given enough information to select proper impulse tube material. Pl. indicate:

1. What is the concentration of HCL and H2SO4 in the tank?
2. What is the pressure and temperature in the tank?

You have indicated tank construction material is CS. Shall I assume in that case the acid in the tank is not at a very corrosive stage? Pl. clarify.
 
R
Not enough information
Tank temperature
Tank Connection size/type
Concentration

It's common to use a transmitter with a diaphragm seal for corrosive liquids so the only material in contact with the process is fully compatible. Given that the tank is MS perhaps there is a suitable fitting material.

Do you have a pipe spec? follow that.

Roy
 
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