Troubleshooting

Bios products are designed to be easy to operate. To speed the process of setting up your Bios device, or to make it easy to deal with some of the most frequent questions customers ask about our products and their operation, we provide a number of helpful tips that may help you resolve any issues you may encounter, quickly and easily.

Please check the product manual for your specific device for additional information.

My gas flow readings are not accurate, what am I doing wrong?
Here is a list of several things to check. If you still have difficulty obtaining accuracy, feel free to contact Bios and talk to our application engineers.

• Verify that the flow source is connected to the pressure port of your meter for pressure sources and to the suction port for verifying suction pumps. The unused port should be at atmospheric pressure with any cap or plug removed. If you are calibrating a gas that requires an exhaust line to vent the measurement gas, ensure that the tubing is of sufficient diameter not to create a pressure drop greater then 5 inches of water.
• Ensure that hose and tube fittings are tight and leak free
• The tubing connecting your flow source (pump, mass flow controller, needle valve, sonic nozzle or restrictor) to the meter should be kept as short as possible. See the FAQ entry on "Connecting Volume".
• Verify that you are measuring the correct type of flow and that the meter is set properly - volumetric or standardized (Note: Does not apply to Defender series, the DC-1 or the DC-lite, which only measure volumetric flow).
• If you are measuring standardized flow, check that the correct standardization temperature is set on your meter (Note: Does not apply to Defender series, the DC-1 or the DC-lite, which only measure volumetric flow).
• Verify that the Sensor Factor on your meter is set to one, unless you specifically want it set to a different value (Note: this applies only to definer and ML models)
• Verify that the PTVM value for the meter is set to one (Note: this applies only to ML models).
• When calibrating MFCs or other flow generators, the gas pressure above the MFC or other flow generator should be 30 PSI or greater
• Temperature variations in the measurement environment should be minimized and the DryCal® instrument should be thermally equalized to the environment for best accuracy.

Why does my Met Lab (ML series) show a different temperature than my lab?
It is normal for your MetLab to display a temperature that differs from your laboratory's temperature. Our calibrators measure the temperature of the actual gas entering the flow cylinder. This is the temperature to which the volumetric reading must be standardized in order to give accurate readings. Room temperature or the gas' original temperature is not important, but the temperature of the actual gas in the cylinder is.

In normal operation in a very stable lab, the MetLab may indicate a temperature slightly higher than the lab temperature due to its internal heating. This is a normal effect, and can be minimized by not charging the battery during critical readings. The battery should be charged overnight prior to using the instrument so that extra heat from the charger is not introduced during the flow measurements. If already fully-charged, the battery can still be left connected to the power line. For the most critical flow readings (beyond specifications), the instrument can be operated on battery alone.

My equipment reads "Over Range".
If the gas flow source, connected to your equipment (such as a sampling pump) exceeds its rated flow range, the display will read "Over Range" and the piston may become "stuck" at the top of the flow cell. For example, DC-Lite model DCL-H is only rated to 30 liters per minute. If you attempt to use the DCL-H to calibrate beyond 30 liters, "Over Range" may appear in the display.

When the gas flow source is disconnected from the flow meter the piston should return to the down position and the "Over Range" display should clear. In most cases, the meter will be unharmed, although it is not recommended to use above its rated flow range, and Bios is not responsible for damage caused by exceeding the meter's rated flow range.

My Bios product's piston seems to "stick" or won't move.
There are several possible reasons why your Bios primary standard's piston won't rise within the flow cell, or seems to "stick" within the flow cell (won't drop to the bottom of the flow cell after a flow measurement):

Possibility #1: Battery
Your Bios product's battery may be too weak to open the internal valve, which releases the piston from its top position within the flow cell once a flow measurement is completed. If recharging the battery does not resolve the issue your battery may need to be replaced Please return your Bios product to Bios for battery replacement. Or, if it's time for your Bios primary standard to be recalibrated, we'll replace the battery free-of-charge as part of our Recertification service.

Possibility #2: Particulates or Corrosion
The interior of your Bios product's flow cell may become "dirty" and particulates, such as dust, can affect the piston's free movement within the flow cell, Or, if your Bios primary standard has been subjected to a corrosive gas, any number of interior parts or mechanisms may be corroded.

Disconnect your Bios product from its gas flow source and then turn it upside down and then right side up a few times. If the piston doesn't move freely and smoothly within the flow cell, then the piston and/or the flow cell interior may be affected by particles or corrosive gas. Return your Bios product to Bios for factory recertification.

Possibility #3: Sunlight
If your Bios product is used outdoors in direct sunlight, the flow cell's internal infra-red sensors may be affected, causing the piston to appear to "stick" within the flow cell, or not move at all.

Simply covering the flow cell with paper or your hand during flow measurements in direct sunlight will solve the problem.

Please note that the Definer 220 is often used to perform field verifications of environmental monitors, and therefore this product comes standard with "sunlight film" adhered to the interior of the flow cell.

However, other Bios primary standards, such as the Defender, Met Lab Series, or our discontinued DC-Lite, DC-2, and DC-1, were not intended for use outdoors, and do not have sunlight film protection. If you routinely use one of these products outdoors in direct sunlight, check with Bios as to the possibility of having sunlight film installed during your next annual Recertification.

Possibility #4: Valve
The valve may not be functioning properly. When this is the issue, often the normal "clunking" sound of the valve is no longer audible (this "clunking" of the valve is not to be confused with the quiet "clicking" sound of the electronic solenoid). This may be due to a weak or dead battery, or it may be a mechanical problem.

Return your Bios primary standard to Bios for our Recertification service, or for basic repair if it's been less than a year since your last recertification (note the "Battery" section above).

Possibility #5: Application
Is a flow source attached to your Bios product? For a suction application, your Bios primary standard's Inlet fitting (Pressure fitting) should be open to ambient air, with its Outlet fitting attached to the flow source through tubing. For a pressure application, its Outlet (Suction fitting) should be open to ambient air, with its Inlet fitting attached to the flow source through tubing.