Explosion Proof Scales with Set-point Options for Munitions Manufacturing

explosive-environment-scale-p-1There are many kinds of munitions manufacturers, ranging from large companies and governments to smaller customer manufacturers. While some manufacture ammunition/bullets, others handle explosives. Munitions manufacture, however, by its very nature always creates a fire or explosion hazard that poses a threat to the safety of people and property.

The Greatest Hazards

Two of the greatest hazards for these manufacturing sites are fire and excessive heat. The majority of ammunition and explosives are sensitive to heat and will react at temperatures substantially lower than other materials like wood, paper or fabric. Even indirect heat generated by a fire, piece of equipment or lighting fixture could cause a reaction that results in an explosion.

The Risk Varies with Material

Fires and explosions will vary in intensity and effect depending on the material involved in the fire. Certain explosives will ignite immediately when introduced to a spark or flame or if subjected to frictional heat or concussion. Some explosive substances may burn freely while others will be subject to explosion while burning. In some cases, such as with solid and liquid propellants, the fire will develop such intense heat that firefighting efforts will be practically impossible.

Classification System

Because electrical equipment can become a source of ignition in these areas, the government has set forth a classification system that breaks down the different types of hazardous locations and the requirements for the electrical equipment that will be used there.

The National Electric Code

The National Electric Code (NEC) defines hazardous locations as those areas Òwhere fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust, or ignitable fibers or flyingsÓ and classifies hazardous locations in three ways: type, condition, and nature.

Hazardous Location Types

There are three types of hazardous locations as outlined by the NEC:

  • Class I indicates locations where flammable gases or vapors are present in such quantities that there is a potential for explosion if an ignition source is present
  • Class II means there is a combustible dust present in the atmosphere than can cause an explosion if introduced to an ignition source
  • Class III describes a location where there are easily ignitable fibers or flyings present due to the materials being handled, stored or processed.

Hazardous Location Conditions

There are conditions under which a hazard may be present:

  • Division I, or the normal condition, means that the hazard is expected to be present in everyday production operations or during frequent repair and maintenance
  • Division II, or the abnormal condition, means that the hazard only introduced to the environment through accidental rupture, breakage, or unusual faulty operation.

The Nature of Hazardous Substances

Classes I and II are further broken down into groups, where materials categorized by their ignition temperature, explosion pressure and other flammable characteristics. Groups A through D organize the gases, vapors and liquids found in Class I locations while Groups E through G organize the dusts found in Class II locations.

Measuring Explosive Material

No matter what explosives you manufacture, there is a ratio or specific formula that must be followed. Often munitions manufacturing is fully, or at least partially, automated. The simplest way to ensure the proper amounts of material are being added to a mixture is with a scale. However, the NEC also outlines the requirements for any electrical equipment being used in a potentially explosive environment. This means that you canÕt use just any scale. All electrical equipment must be tested and approved by recognized testing laboratory for use in a specific hazardous location.

ArlynGuard Explosion Proof Scales

Our ArlynGuard B, C, F, and P scales have one or more components that have been tested and approved to be Intrinsically Safe for use in an impressive range of hazardous locations including:

•    Intrinsically safe for use in Class I, II, III; Division I; Groups A through G
•    Non-incedive for use in Class I; Division II; Groups A through D
•    Suitable for use in Class II; Division II; Groups F & G
•    Suitable for use in Class III; Division II

Each ArlynGuard scale is equipped with one or more of:

•    Model MKE-5-IS(-C) Digital Weight Indicator System
•    Load Cell Models 620-300-IS, 620-100-IS, 620-50-IS, 620-25-IS, 620-10-IS, 520-10000L-IS, 520-5000L-IS, 520-5000IS, 520-2500-IS, 520-1250-IS, 320-500-IS and 320-250-IS

which are FM Approved components as per Approval Standard 3600, 3610, 3611 and 3810.

Choose from a variety of bench, cylinder, platform and floor scales. Capacities and resolutions range from 5 lbs x .001 lb to 20,000 lbs x 5 lbs.

Process Automation

An optional feature, our setpoint output provides simple batching and PLC type functions. Set up to eight target weights at a time and use them to turn other equipment on and off. Feeders, mixers, motors, valves, solenoids and other devices may be controlled using solid state relays that are operated by the setpoint outputs. Through the setup menu, youÕll have the ability to input formulas that control the output lines based on the weight applied to the scale platform. With a large internal memory, many different formulas can be saved and recalled as needed.

Inventory Control

Keeping accurate records of your raw and processed materials has never been simpler. We offer a variety of data communication and storage options, but not all of them are appropriate to use in a hazardous environment, so be sure to let us know what youÕre working with so we can suggest the appropriate output. Options include USB, flash drives, Wi-Fi, Ethernet, Cloud and RS-232.


In business for over 30 years, Arlyn Scales has earned its reputation as a leader in the design and development of industrial weighing solutions. As a U.S.-based, factory-direct manufacturer, we offer a superior product at competitive prices. We also have the ability to provide custom weighing solutions and gladly welcome OEM interest. If youÕre unsure which ArlynGuard scale will best suit your munitions plant, contact Arlyn Scales today. Our expert staff is standing by to field your questions and help guide you to the scale that best meets your needs.