Methods of chemical transportation and delivery have changed over the past few years due to pressure to lower on-site inventory and improve supply chain reliability. This is driven by the need to ensure a constant supply of treatment chemicals while avoiding hazardous chemical quantity reporting requirements.
As a result the intermediate bulk container (IBC), commonly called the tote, is evolving into a primary chemical delivery and management tool. New level sensors and control systems have been developed to help with management of chemicals in these smaller containers.
The IBC typically is a forklift compatible square tank constructed of either metal or plastic. They range in size from 240 to 440 gallons. Their modular design allows IBCs to be stacked to maximize inventory and minimize floor space requirements. The chemical supply company retains ownership of the reusable containers, picking up the empties after delivering the full ones.
?What is happening is a substantial revolution in the supply chain. Chemical distributors and municipalities are in the process of automating the monitoring, ordering and delivery of chemicals,? said Scott Olson, president of Flowline Inc.
In a typical application, a primary IBC is permanently located and hard-plumbed into a chemical metering process. A secondary IBC is stacked on top and connected to the primary unit by a gravity-feed hose. When the primary IBC is emptied, a user manually opens a ball valve to drain the secondary IBC into the primary. The operator must then notify purchasing to order another container of the chemical. While simple, this manual system can lead to shortages.
New technology is available to transform IBCs into a hands-free system that can minimize problems such as running low on a chemical or carrying excessive inventory.
Automating the IBC process requires a level sensor, a fill valve and a programmable logic controller (PLC). The level sensor is located in the primary IBC and the valve is installed in the gravity feed line. As a chemical in the primary IBC reaches the low-level condition, the primary IBC is filled and a purchase order is issued to the chemical distributor. While most of these system components are available, the missing link has been a level sensor that meets typical IBC requirements.
Flowline, a manufacturer of chemical inventory monitoring equipment, has introduced its LA15 series Ricochet™ ultrasonic level transmitter designed for IBC chemical applications. The compact sensor design stands only 3.5 inches above the tank, offering plenty of clearance between the top and bottom IBCs. With non-contact technology, the sensor is suitable for highly corrosive acid, caustic and chemical applications.
The unit pulses an ultrasonic sound wave five times per second from the base of the transducer. The sound wave reflects against the process medium below and returns to the transducer. The microprocessor-based electronics measure the time of flight between the sound generation and receipt, and translates this figure into the distance between the transmitter and process medium.
The PVDF transducer has only a 3.5-inch dead band to maximize the IBC filling capacity. In addition, an 8-degree beam diameter enables the sensor to function within the restricted space of the IBC. The bulge on the top of the IBC is about 3.5 inches and the legs on the tote?s four corners extend upward to protect the unit from damage when the forklift is setting the upper replacement tote into position.
The unit measures the chemical level continuously and feeds that information back to the controller or to an indicator. The PLC on the relay card actuates the valve between the primary and secondary IBCs to dump chemical from the upper to the bottom IBC when needed. When the top tank is empty, the PLC can turn on a local alarm to alert the facility operator to replace the top tank.
?Some facilities are putting in an autodialer to send a purchase order to the chemical distributor to send more chemical. It can be in the form of a fax, an e-mail or a pager notice or any other format the system defines,? said Olson.
A supply voltage of 12-36 vDC powers the LA15 transmitter. The enclosure is made of polypropylene (PP) and the transducer is made of polyvinylidene fluoride (PVDF). The sensor arrives from the factory pre-calibrated and pre-assembled.
To eliminate older sight glasses, Flowline also has developed an IBC measurement and indication package. The company?s AK10 series Ricochet ultrasonic level transmitter includes an LED digital indicator for local inventory readings in inch, gallon or percentage of span values.
In a typical application, a forklift removes the tote from a flatbed truck and moves it to the storage and use location.