Overview
As dog owners, we treat our pets as we do our children, taking care that the food we give them is not only filling and nutritious but contains only high-quality ingredients sourced and processed in ways that meet our exacting standards.

For many owners, far in the past are the days of grabbing any old bag of kibble off the shelf and feeding it to Fido or Ginger. Dog owners today are making informed choices in their purchases of pet food, such as whether the ingredients are all-natural or organic, whether they contain allergens to be avoided, which proteins predominate in the mix, etc. Not only are owners increasingly educated about what goes into their dogs’ food, they are faced with many choices when it comes to exactly what form the food will take.

Types of Dog Food
Major pet food types available to contemporary dog owners, from a wide array of manufacturers, include dry food, semi-moist, canned, raw, and freeze-dried food.

Dry food, commonly known as kibble, is the most prevalent type of dog food on the market. Semi-moist food is served either on its own or added to kibble for a variety of tastes and textures. Canned food is a moist product with a long shelf life. Raw food appeals to owners who believe that an uncooked all-meat diet is closer to what dogs would have eaten in the wild, before they became domesticated. Raw foods may be produced and sold as either fresh, fresh frozen, or freeze-dried.

Freeze-Dried Dog Food
The freeze-dried dog food segment--including 100% freeze-dried meals, so-called “kibble+” (dry kibble mixed with freeze-dried components), and freeze-dried treats, such as beef liver and other types of training tidbits--currently commands only a niche share of the ~$30 Billion U.S. dog food industry, but it is rapidly growing in popularity among owners seeking, as in their own diets, to avoid highly processed foods.

Purchasing freeze-dried proteins, whether cooked or raw, as well as fruits and vegetables (which are typically freeze-dried in a raw state), allows owners to provide their pets with minimally processed, nutrient-rich, natural foods. Freeze-drying quality ingredients makes for an easily transportable, shelf-stable tasty food that does not require refrigeration.

Gas Usage in Freeze-Dried Food Processing and Packaging
Food safety is as important in the pet food industry as it is in the manufacturing and distribution of human-grade foodstuffs.  Proper temperatures must be maintained in order to prevent mold and bacteria growth resulting from, among other things, improper cooking and cooling temperatures, as well as insufficient or excessive moisture.

Quality control and safety concerns dictate that, because of their rapid cooling and freezing properties, liquid nitrogen (LN2) and liquid carbon dioxide (liquid CO2) be used in pet food production to uniformly cool proteins after cooking, and to freeze them as part of the freeze-drying process. Once properly chilled, the proteins and other ingredients that go into a freeze-dried dog food product are quickly frozen in blast freezers using LN2 or liquid CO2.  After freezing, they are placed into vacuum drying chambers for some 12 hours, until the drying process is complete (i.e., essentially all moisture has been removed), following which the food is ready for packaging.

To prolong dog food shelf life (by inhibiting the growth of mold and bacteria which thrive in oxygenated environments), nitrogen is injected to displace oxygen from the product packaging.The addition of nitrogen during the packaging phase also provides a cushion to protect the contents from settling and breakage that can occur during shipping and handling.

Oxygen Monitors Can Improve Safety in Pet Food Manufacturing and Packaging
While their use is essential in the production of freeze-dried dog food, nitrogen and carbon dioxide can pose health risks (including death by asphyxiation) to employees working in the industry. Nitrogen and carbon dioxide are both odorless and colorless, and they displace oxygen. Absent appropriate monitoring, workers would be unable to detect a leak if one were to occur in a gas cylinder or line. Conversely, by utilizing a top-quality oxygen monitor, safety and production personnel can track oxygen levels and detect leaks before workers’ health is jeopardized.

PureAire Monitors

With PureAire Monitoring Systems’ dual oxygen/carbon dioxide monitor, pet food producers can track levels of oxygen and detect nitrogen or carbon dioxide leaks before workers’ health is at risk. PureAire’s O2/CO2 monitor measures oxygen and carbon dioxide 24/7, with no time-consuming maintenance or calibration required. PureAire’s monitors can handle temperatures as low as -40C, making them ideally suited for environments, such as pet food processing plants, that use liquid nitrogen and carbon dioxide.
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​Built with zirconium oxide sensor cells and non-dispersive infrared sensor (NDIR) cells, to ensure longevity, PureAire’s O2/CO2 monitors can last, trouble-free, for over 10 years under normal operation conditions.

Overview

Vehicles powered by gasoline and diesel account for emissions of dangerous air pollutants and contribute to the presence of greenhouse gases. Consumers, businesses, and public entities looking for environmentally friendly alternatives to gasoline and diesel-powered cars and trucks have viable choices beyond the well-known battery electric and plug-in hybrid electric variants.  Other options in use today include vehicles powered by natural gas, as well as, on a more limited basis, those powered by hydrogen fuel cells.

Natural Gas Vehicles
Natural gas can be used to power all classes of vehicles, including motorcycles, cars, vans, public transit buses, light and heavy-duty trucks, etc.  Most natural gas vehicles (NGVs) run on either compressed natural gas (CNG), which is typically used for light-duty vehicles (such as motorcycles, cars, taxi cabs, and light trucks), or liquified natural gas (LNG), used in heavy-duty vehicle applications (including public buses, garbage trucks, and the like).

CNG vehicles store natural gas in tanks, where the fuel remains in a gaseous state. Vehicles using LNG can typically hold more fuel than those using CNG, because the fuel is stored as a liquid, making its energy density greater than that of CNG. That makes LNG well-suited for heavy duty commercial trucks requiring the greatest possible driving range. Regardless, because of the lower density of natural gas (whether CNG or LNG), the driving range of NGVs is generally less than that of comparable vehicles powered by gasoline or diesel.

As such, and excluding the commercial and municipal fleet sectors, where fuel sources can be assured, confidence in ability to timely access refueling stations must be a concern for drivers (or potential drivers) of NGVs.

The first vehicles converted to utilize natural gas appeared in the late 1930s, though most of the rapid growth in NGV usage has taken place in recent years. According to the Natural Gas Vehicle Knowledge Base, there are over 27 million NGVs currently on the road worldwide (compared with as few as 1 million as recently as 2000), with over 70% of the present total in the Asia-Pacific region (and only about 225 thousand in North America as of 4/30/2019).

In addition to the reduction in greenhouse gas emissions inherent in choosing natural gas over conventional gasoline and diesel fuels, some businesses and municipalities seeking to meaningfully reduce reliance on fossil fuels are going even further, by focusing on renewable natural gas (RNG), including gas derived from decaying garbage, to power
vehicles subject to their authorities.  Indeed, in May 2019, the City of Seattle, Washington announced that the trash truck fleet servicing Seattle will now include some 91 Waste Management vehicles powered by RNG generated by decaying trash from U.S. landfills.

Hydrogen Fuel Cell Vehicles

Importantly for the environment, hydrogen fuel cell electric vehicles (FCEVs) produce no tailpipe emissions.  Fuel cell technology has been around since at least the late 1950s, when Allis-Chalmers tested an FCEV farm tractor, followed some years later by GM’s prototype hydrogen FCEV Electrovan in 1966.  FCEVs use a propulsion system whereby energy, stored as pure hydrogen gas, is converted to electricity by a fuel cell.

Initially, the fuel cells and associated piping were quite bulky (reducing the 6-seat GM Electrovan from a 6-seat van to a 2-seater that could barely accommodate 2 adult passengers), heavy (reducing range and acceleration, such that the Electrovan, which was never produced for sale, had a top speed and range of  only about 70 mph and 120 miles, respectively), and too expensive to mass produce.  As a result, meaningful FCEV production has lagged until well into the 21st century, when technological innovations have at last begun to make it possible for the FCEV concept to become a functioning reality.

Though FCEVs, and the hydrogen fueling infrastructure (i.e., stations equipped to pump hydrogen gas) necessary to support them, remain in a relatively early stage of development, certain major automobile manufacturers (including Honda, Hyundai, Toyota) are now offering a limited number of FCEVs to the public in certain markets (chiefly within California) where hydrogen refueling infrastructure is already in place, and passenger FCEVs currently in service now have a driving range between refueling of some 300 miles.

However, until retail refueling infrastructure shows a marked increase, most of the anticipated growth in hydrogen FCEV usage is likely to come from the municipal and commercial fleet sectors. By way of example, Toyota and Kenworth have recently announced development of a 10-vehicle zero emissions heavy-duty FCEV truck fleet to be put into service at the Port of Los Angeles.

Refueling and Maintaining Alternative Fuel Vehicles

While far fewer in number, refueling stations and equipment for vehicles powered by natural gas (approximately 1,900 service stations in North America) and hydrogen (no more than 50 service stations in North America, mostly in California, can accommodate hydrogen FCEVs) are similar in appearance to conventional gas stations and pumps, with large tanks from which drivers pump into their vehicles either natural gas, on the one hand, or hydrogen on the other.

According to the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy, proper maintenance of NGVs requires that the fuel storage tanks be inspected regularly, following accidents, or when there has been suspected damage.  NGV users must also be aware of end-of-life dates of their tanks, so that the tanks can be properly decommissioned as and when appropriate. Moreover, fuel filters should be inspected and, if necessary, replaced on a yearly basis.

Hydrogen FCEVs are maintained in much the same way as any other electric vehicle, including scheduled maintenance, and, if necessary, replacement of electric components and suspension parts. For a major overhaul, a vehicle will need to be serviced at a so-called “hardened shop”, at which there are specific requirements, including the presence of combustible gas monitors, curtains around the work area, and explosion-proof lighting fixtures.
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Gas Detection Monitors Can Improve Safety in Alternative Fuels Servicing Facilities