Page 48 - OHS, October 2021

IH: INDOOR AIR QUALITY
Vacuum conveying systems contain respirable dust from source to destination in a closed system preventing respirable dusts from escaping into the plant environment in the first place.
to climb up to a large hopper to fifill it manually, preventing slip and fall hazards as well as exposure to respirable dust.
ThThe new system, a compressed-air powered vacuum conveying system, utilizes a bulk bag unloader, adapted to accommodate the oddly shaped super sacs, to feed the fifine flflour into the system directly without manual exertion, and without dust. Although the system did reduce housekeeping labor, the customer said the bulk of the gain came through safety and efficiency. Additional safety and cost benefits of the new system that the customer noted were its small footprint, the reduction of noise by eliminating electric motors to run the system and reduced energy costs as a result of eliminating the motors.
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manufacturer that deals exclusively with vacuum technology and how that technology interacts with materials ensures that potential challenges are anticipated and addressed prior to equipment delivery. Every customer likes to do things a little bit differently, so there is no one size fits all approach to vacuum conveying. Specific components of each system are selected based on a customer’s objectives and material requirements.
Experienced vacuum technology experts engineer systems from their storied knowledgebase without having to reinvent the wheel. As a result, they are able to present customers with different options that allow them to determine the level of automation they want and calculate ROI accordingly. More automation costs more upfront, but it costs less in the long run due to reduced labor costs or an increased ability to run more batches in an hour if the system is automated, or it is eliminating an ergonomic or safety issue and the costs associated with an accident. Product quality can also be a factor with less waste and better customer satisfaction.
The following are several examples of how vacuum conveyors solved common industry challenges specific to customers’ needs. It is important to note that when working with pharmaceutical powders, silica, lead, asbestos, beryllium, hexavalent chrome and other potentially hazardous respirable dusts, a HEPA secondary filter cartridge, rated 99.97 percent efficient at 0.3 micron is utilized with vacuum conveying systems. When a noodle manufacturer made the switch from handling 50-pound bags of flour to handling 2000-pound bulk bags, an older pressure-based conveyor system, which transported 20 tons of very fine flour per week from a hopper through a volumetric feeder to a mixer, no
longer satisfied the company’s needs.
In pressure-based systems material is pushed through the
conveying line, and if there are any leaks in the system dust escapes outwardly into the environment making a mess and exposing workers to potential dust hazards. With vacuum conveyors material is pulled through the conveying line, and in the event of a leak, the leak is inward, containing dust within the closed system. The primary objective of the noodle producer was to accommodate new super sacs and eliminate the need for workers
Compressed-air-powered vacuum conveyors are the most economical and energy efficient method to convey materials. Operating on the Venturi principle, these systems create their own vacuum without motors or moving parts, making them intrinsically safe. No moving parts or motors also means that units generate no heat and last longer because there are no parts to fail. The vacuum conveying system supplied to the noodle producer is fairly simple, delivering flour from super sacs to a mixer; however, delivery of minor and micro ingredients to process vessels requires a bit more engineering.
Adding minor and micro ingredients into process vessels has traditionally been done by hand-scooping and measuring, especially within the pharmaceutical industry. Hand-scooping of active pharmaceutical ingredients exposes workers to dust from harmful drugs that can produce adverse health effects beyond occupational lung diseases (OLDs). Batch weighing, or multi- ingredient handling, has been around for more than 40 years, but the pharmaceutical industry has been slow to adopt it, due to confusing regulatory language. As the FDA continues to clarify regulations, more and more pharmaceutical processors utilize this technology to protect workers health and achieve accurate formulation control.
Utilizing state-of-the art controls technology, sophisticated vacuum conveying systems employ loss-in-weight or gain-in- weight methods to meter multiple minor and micro ingredients into the conveying line. In one instance, five minor ingredients metered into the conveying line simultaneously by piping the entire conveying line together and metering ingredients from bulk bags to feeders and then into the conveying line to a mixer.
Another application metered is micro ingredients by loss- in-weight into a common weigh hopper. With this method, the weigh hopper is suspended directly above a mixer where a valve opens and discharges ingredients directly into the customer’s process. Manual loading of powders and bulk solids into mixers is a recognized hazard across all industries and although materials used in food, pharmaceutical or chemical applications may be vastly different, basic vacuum conveying technology is relatively the same across industries.
While it is not feasible for some manufacturers to completely eliminate manual handling of materials, inventive design and application of vacuum conveyors provide innovative solutions that minimize exposure. In an ongoing effort to amplify safety and get ahead of rising raw materials costs, a major paint manufacturer purchased a vacuum conveying system with the primary goal of returning captured materials from a dust collector back into the process to reclaim expensive ingredients
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44 Occupational Health & Safety | OCTOBER 2021
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