Produce Disinfectant Management Using Walchem WIND Webmaster Control System

Submitted by Scott Severse || Valin
Grocery stores require produce to be disinfected before being shipped to their outlet on a regular basis in order to ensure cleanliness before it is sold to their customers.  If left untreated, fresh fruit can be subject to a number of different contaminates that can ultimately adversely affect the consumer’s health. As the public is more conscious than ever about the substances and chemicals that they ingest, ensuring that produce does not harbor microbes is critical. 

This disinfection is typically achieved through use of an oxidant such as chlorine, chlorine dioxide, PAA or ozone.  In addition to controlling this oxidant, readings must be data logged, alarms must be set on out-of-range conditions in the treatment process and a mechanism must be put in place to shut down the line when there is a clear issue with the operation.  Furthermore, in order to ensure the health of their customers, grocery stores are typically asking for all of this information to be presented to them by their suppliers.  Operators that are in charge of applying the oxidant and documenting all of the key data points that are looking for efficient, simple ways of doing so.  Valin recommends a solution that is both simple and reliable and doesn’t require a sophisticated knowledge of automation to operate, the Walchem WIND Webmaster Control System.

The WIND Webmaster Control System is the ideal solution for the challenge of produce disinfection, as it has a flexible multi-input/output platform, a wide range of analytical sensor measurement capabilities and an extensive assortment of integrated communications and data handling features.  Valin also strongly recommends the Webmaster WIND due to its convenience and ease-of-use.  Rapid corrections can be easily made without the use of costly programmers. A separate data-logging device is unnecessary with the Webmaster WIND.  The data can be automatically retrieved through the convenience of a standard USB flash disk or accessed if the unit is on-line.  Additionally, the Webmaster WIND doesn’t require a software programmer for customization to a specific application.  This is unlike most PLC’s or similar devices and can reduce upfront costs and eliminate the need for software maintenance, a recurring expense.

Flexibility is another crucial advantage of the Webmaster WIND.  The controller allows for SCR (sensor-control-relay) mapping in order to allow the user to select any sensor input and control method and assign them to a relay.  The Webmaster WIND can be programmed for nearly any water treatment application as it has up to 21 user-defined inputs.  In addition to four direct analytical sensor inputs, the controller can add eight analog inputs and twelve digital inputs.  It has contains eight relay outputs. This allows for many configurations that so you can customize of your process.

The reporting by the Webmaster WIND has also been designed to be customized to fit the user’s specific requirements.  System summary reports outline current conditions on the line as well as alarms.  To account for historical trending, a datalog report is sent on a regular basis that you choose.  Alarms can be adjusted to be sent by email and cell phone text.  The data logging is done rapidly (as rapid as every 15 seconds), leading to increased efficiencies and the ability to troubleshoot the systems.

The Webmaster WIND contains four sensor inputs for the control of pH and disinfection chemical, conductivity or salinity. The oxidant sensor inputs utilize Walchem’s amperometric disinfection sensors.  Valin recommends using this particular line due to its effectiveness, speed, reliability and their compatibility with the WIND Webmaster Control System.  The direct reading amperometric sensors work with a varying range of concentrations for free or total chlorine, chlorine dioxide, ozone, peracetic acid and hydrogen peroxide and report in ppm. 

For maximum reliability and control, an electronic metering pump is key.  Specifically, Valin recommends the EWN-R Series of Electromagnetic Metering Pumps offers superior high speed dosing capability with more standard features.  When needing to handle a chemical feed application, an operator requires flexibility to meet the demands of the process. The EWN has the required set of features including: universal voltage, optional auto- degassing valves and a digital controller with an 1800:1 turn down ratio which means high accuracy.  The E-Series pump operates up to 360 strokes-per-minute and has adjustable stroke length further increases its ability to refine output, adding to the pump’s versatility and consequently, its desirability.  Another aspect of a pump that experts are looking for is the check valve performance.  Superior check valve design wil guarantee fast priming and reliable performance.  Additionally, the compression ratio needs to be high. Its importance cannot be understated.  The compression ratio affects the pump’s ability to properly prime and vent which reduces the chances of vapor lock caused by off-gassing chemicals.

 

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