A large company who supplies high quality titanium metal products was searching for a reliably way to detect any plugged chute conditions that may arise in their process. Titanium is used in hundreds of diverse aerospace, industrial and emerging applications where no other metal is as reliable or economical, especially on a lifecycle costing basis.

The customer was looking for a level control to be successfully used as a plugged chute detector; the customer had experienced problems with RF probes from another manufacturer. Plugged chute detection is critical to make sure that material is flowing properly through a process. A plugged chute condition can cause problems with transfer rates, mix ratios and production “down stream”. Monitor offers several options for plugged chute detection (click here for more information). For this situation, the high-temperature SafePoint® rotary paddle bin indicator was the best choice.

The target materials are Rutile Ore with a bulk density of 150 lbs per cubic foot and Petroleum Coke with a bulk density of 53 lbs per cubic foot. The material characteristics of the Rutile Ore can be described as having a “sand texture” and the Petroleum Coke is “granular”.

This application is made even more challenging due to the extremely high temperatures involved, the ambient temperature ranged from 100 degrees F to 150 degrees F and the internal process temperature could be as high as 750 degrees F. But wait, this gets even better; the internal air in the feed pipe being monitored for a plugged chute condition is a gaseous chlorine, which if combined with moisture of any kind creates Hydrochloric Acid!

The Sales Engineers with Ball Sales, the Monitor rep in CA, OR, WA, AZ, NM, NV, worked with the customer by gathering additional details and suggested that the best solution would be for the customer to install a high-temperature SafePoint rotary paddle bin indicator. The hi-temp SafePoint unit can be used in applications up to 750 degrees F.

The SafePoint will not be challenged by the fluctuating dielectric constant of the target material or the possible changing temperatures that caused the issues with the RF probe they first tried.

The SafePoint® rotary paddle point level sensor is a self-validating device that detects material presence plus continuously monitors its own ability to function. Should the self evaluation detect an internal fault, an output will react accordingly. This includes fault due to power loss.

The built-in microcontroller performs self-validating diagnostics and monitors both shaft and motor mounting plate rotation. This allows the SafePoint to easily distinguish between material presence and any electrical and mechanical failure of the unit. When material presence is detected, the SENSE relay changes state and the drive motor is de-energized to extend motor life. This output is available to control a process function or alarm circuit. When the material level drops, a tension spring returns the drive motor to its original running condition and is reactivated.

Figure 1 - Hi-Temp Safepoint used in Titanium Application


Figure 2 - SafePoint, Principle of Operation


A unit failure is detected by sensing a lack of shaft rotation while material presence has not been detected by rotation of the motor mounting plate. In a failure condition the independent FAULT relay will change state. Monitoring the state of both the SENSE and FAULT relays provides the most flexibility for control and monitoring that is beyond being just “fail-safe”.

Features of the SafePoint® include:
> Rugged cast aluminum construction
> Motor shut-off when paddle becomes impeded by material to increase motor life
> Twist On/Of Cover
> Choice of process connections & accessories
> High Temp model available
> Hazardous location approvals available

Typical applications include High and Low level sensing in bins, silos, tanks, hoppers, and other vessels. The SafePoint can also be used for plugged chute detection. It can be utilized for high level indication of materials over 10 lb/ft3 (160 kg/m3) and for low and intermediate level indication for materials over 5 lb/ft3 (80 kg/m3). Target materials include but are not limited to: Pellets, Powders, Cement, Sand/Gravel, Feed/Grain, Plastics, Coal, Metals, Food Ingredients, Resins, and Sawdust.

For more information, please visit
http://www.monitortech.com/product_p_fails.shtml
or call us in the USA at 800-766-6486 or from anywhere at 630-365-9403. Also, check out our Level Measurement blog at http://monitortech.typepad.com.

Scott Bonine Director of Sales