Autorodders have ZERO effect on Pressure Transmitters

Categories: | Author: Clearguard Administrator | Posted: 30/03/2009 | Views: 5307


Safety shut down system where 2 out of 3 pressure transmitters must accurately measure the process variable at all times. When 2 transmitters measure an irregular process variable i.e. outside set points or no process variable, due to blocked tapping points, an automatic unit shut down occurs.
Titanium Tetra Chloride at 180ºC passing through a heat exchanger. Any moisture content and cooler surfaces cause the product to scale.
Current installation includes double block and bleed tapping point isolation valves with integral manual rodding tool. Extremely hazardous procedure whereby operators must manually rod out tapping point each shift to ensure transmitters are measuring accurate process variable. 
Nitrogen purge is pre-heated to a minimize the possibility of scale build up. This purge is used not only as a barrier between process and pressure transmitter but flows at a rate to assist in keeping the tapping point clear. 
Regular rodding gland failure occurs requiring regular maintenance and exposing operators to chlorine gas risk.
Replace hazardous manual rodder with Clearguard Autorodder. Set stroking frequency to one cycle every 12 hours.
Figure 1
As can be seen from Figure 1 – Pressure Transmitter Raw Data, the Autorodder was stroked 3 full cycles i.e. passing through the tapping point 6 times between 3:15pm and 3:18pm.
There was zero effect on process variable measurement.
Nitrogen purge flow had been reduced to bubbles per minute flow rate and was no longer heated, significantly saving energy costs.