The next utility challenge is the water bill. Dave Schwanz of Durable Controls in Wisconsin supplies water meters to many companies in the beverage and dairy industries. This article includes many of his suggestions for the purchase and use of water meters in bakeries and snack food facilities.
One of the cost issues for food operations has been the utility using the water meter reading of incoming water as a billing number for discharge water when in fact a significant amount of water is used in the product and is not discharged. As water discharge costs increase this margin may be a significant cost.
In addition to incoming water meters, meters should be installed at critical points in the process: at dough mixers (this should be a given) and wherever water is added to the process, including at splitters and seeders. In addition, meters may be installed at auxiliary operations, including CIP systems, boilers, cooling towers, sanitation hose stations and pan washers, as well as on effluent lines leading to on-site pre-treatment works and/or publically owned treatment works. By employing an estimate for water used by employees at toilets, sinks and showers, about 25 gallons per person per day, a bakery is able to estimate the wastewater discharge rates in the absence of a wastewater flow meter.
Metering provides information that in conjunction with volumetric evaluation or pricing provides an incentive for water conservation and helps to detect water leaks in the system providing a basis for repair orders.
Mr. Schwanz suggests that the most important criteria for selecting a water meter are line size, flow rate, pressure, temperature and the accuracy required. Line size in bakeries and snack food operations usually ranges from ½ inch, ¾ inch to 1 inch. The meter accuracy required relates directly to cost of the meter. Ingredients may require a more accurate measure, for example ounces, than points in the wastewater flow, which might be accurate to ½ gallon.
Self-draining and cleanable meters should be considered if they are monitoring ingredient flow that could become clogged.
Most meters measure the flow rate, and integrate that rate over time to calculate volume. The costs of metering include costs to purchase and to install meters, retrofit vs. new installation; read and process the data; parts and replacement costs. Adding additional cost, annual calibration of water meters may be required by large customers whether the supplier of the meter agrees or not.
Mr. Schwanz suggests that the two most likely choices for a bakery or snack food operation are mechanical meters and magnetic flow meters.
Mechanical water meter pricing starts in the $60 to $70 price range. Basic mechanical meters send information to displays or dials that must be interpreted. Reading the meters adds labor cost as a factor in the purchase and use decision.
Mechanical meters work when water physically displaces the measuring element in direct relation to the amount of water that passes through the meter. These meters are accurate at low to moderate flow rates found in bakeries and snack food manufacturing. The meter is measuring velocity of the full line and should be kept full and controlled with a downstream shut-off or some source of back pressure to ensure the pipe remains full at all times.
Pricing for a mechanical meter with an electronic output begins at about $600 for a 1-inch line. These meters generate digital information that may be used by other information systems. The water meter is able to send information to a totalizer that may cost $300 for the facility water meters or, for batch process control, as much as $1,500. The output log may be set to the production schedule.
Magnetic flow meters (mag meters) are velocity-type water meters, which use electromagnetic properties to determine the water flow velocity. Pricing starts at about $2,000. Mag meters use the physics principle of Faraday’s law of induction for measurement, and require AC or DC electricity to operate the electromagnets. These meters can measure waste-water, since there is no mechanical measuring element to get clogged. Experts note that, stray electrical energy flowing through the flow tube may cause inaccurate readings; therefore most mag meters are installed with either grounding rings or grounding electrodes to divert stray electricity away from the electrodes inside the flow tube that are used to measure the flow. All meters with an electric output need to be kept dry, so installation may require an additional cost.