How We Developed Wireless Level Sensors for Waste Chromatography Solvents

We first came across the need for waste solvent level detectors a few years ago with a large pharmaceutical lab in the Northeast focusing on therapeutic proteins.  They have dozens of Akta and HPLC systems running tests simultaneously and each system generates toxic waste solvents which collect in carboys under the lab benches. 

Argento Scientific was already supplying them with equipment to capture and seal up the waste, but we didn’t offer a way to warn when the container was about to fill up.  The trouble for our customer was that it was difficult for any one person to monitor dozens of waste containers as they filled up.  They asked us if we offered a waste level warning system that worked with our existing waste capture equipment.

Carboy under lab bench

The Problem

Like with most labs, the waste solvent containers fill up for a day or so and then are emptied into a central reservoir.  From there the solvents are removed and safely disposed.

The containers sit under the instrument on the floor and are often inside a tray, so you can’t always see the whole container.  The containers themselves are often made of a plastic that’s partly opaque, like HDPE, and the liquid in them is clear, so it’s hard to see what the liquid level is.  Sometimes you had to give the container a light kick to move the liquid just to see the level. 

Then there were the overflows. The floors in the lab are smooth tile, so any fluid that got on the floor was hard to see and the fluid created a slip hazard. Depending on the tests being run, the waste chemicals can be toxic, corrosive, flammable or all three.  A spill could require evacuating the lab, and cleaning it up wasn’t like cleaning up a spill in your kitchen. There was paperwork! 

To summarize, here are the issues:

  • Hard to see the containers under the bench
  • Lots of containers to monitor
  • Containers are semi-opaque and collect clear fluid
  • Spills produce slip risk
  • Possible toxic fumes  – need to be captured and scrubbed, a spill can cause exposure
  • Possible fire hazard if liquid or fumes escape
  • Spill clean-up is difficult
  • Any spill is a safety violation

The Solution

We started by looking for off-the-shelf products, and there seemed to be lots of options.  Cars have gas tank gauges, and similar systems operate in municipal water towers, refineries, milk processing facilities, breweries and so on.  But waste HPLC solvents present unique requirements.  Here are some of the issues and how we solved them:

Power source – Labs have a lot of equipment, so electrical outlets are scarce.  We could use batteries for power, but changing out batteries in lots of systems, or charging batteries, could be cumbersome.   We opted for sensors that power themselves with ambient light.  In addition to not relying on outlets or batteries, this approach has the advantage of using very low power.  The sensors don’t use enough electricity to generate a spark, and on top of that all the electronics are sealed in an enclosure.  

Alerting Mechanism – Lighting up and/or making noise at the nearly-full carboy doesn’t help if no one is near that particular system.  In fact if people were always right near a particular system they probably wouldn’t need the warning system in the first place.  The system we developed sends wireless signals from the carboy to one or more remote buzzers.  The buzzers can be near the system, or near where the operator sits, or both.  We also offer the capability to notify a cell phone via text message, so the operator doesn’t have to be in the same building, or even in the same town. 

Attaching to the Carboy – Carboys come in a variety of sizes and openings.  Users don’t want to throw away the carboys they already have and get new ones in order to accommodate the level detection capability.  Not an issue.  We supply caps to fit most kinds of carboys and our sensors work with all of them.  Our caps also connect to the different kinds of tubes that exit the chromatography systems.

Typical installation set up of Argento Scientific Solvent Waste Level Detectors

For more information on the Argento Scientific Waste Solvent Monitoring System check out our website or give us a call at 203-343-7679.