One of our customers builds ships, many of which service the oil and gas industry and offshore drilling rigs. One of their main jobs is to deliver drilling mud to the rigs.
Just like any other valuable chemical, drilling mud inventory must be tracked to keep operations running smoothly. They do this with level sensors to keep tabs on the ship’s liquid mud storage tanks during filling, emptying, and transport.
After trying a variety of other technologies, our customer approached us for some help. Measuring mud levels can be a challenge, especially on ocean vessels. Ultrasonic and radar sensors required too much programming and continuous maintenance in order to achieve reliable readings – while capacitance and hydrostatic pressure simply did not work.
Everything our customer tried was failing. They were at the end of their level measurement rope.
Experience Matters
Here at APG, we have a lot of experience with measuring drilling mud. We have determined that using float and stem configuration, such as resistive chain or magnetostrictive, is the best way to go. In fact, we have thousands of our RPM probes on drilling rigs all over North America. So this is what we proposed to our ship building customer.
But we weren’t out of the woods yet. We were unable to mount the sensors the way we normally would – from the top of the tanks. The tanks were installed right below the deck of the ship with no space between the top of the tank and the deck. All that we had to work with was an existing 1.5 inch entry port located on the side of the tank, just below the top. We were going to have to design a special side mount unit.
In the past we have designed special probes to have a 90 degree bend in them allowing for a side mount. This worked well enough but often resulted in new challenges during installation. Doing a 90-degree bend in this application with 15 ft. tall tanks would have made the installation of the units extremely difficult.
So this plan was scrapped.
A Perfect Solution
Then came the simple, yet brilliant, idea. Instead of building the stem to have a 90-degree bend, we designed the unit to have a detachable cable run from the stem to the housing. Here, we could easily achieve a 90-degree bend at the cable.
Since the sensor did not go all the way to the top of the tank, the whole unit would be submerged in the mud on occasion. To protect the sensor, we sealed the connection to the 90-degree pipe fixture. Stainless steel pipe was used to protect the remaining cable inside of the tank. Finally, instead of using mounting threads or a flange to stabilize the unit, brackets and clamps were used. This configuration has proven to be a simple but effective way to achieve a side mounted sensor.
If you have a level measurement application that is difficult, put our Measurement Experts to work for you. Whether by email, live chat on this website, or by phone, please reach out to us. Our decades of experience will probably come in handy for you, just as it did with our friends in the shipyard.
