As we ring in the new year 2025, a significant change is coming for several heating, ventilation, air conditioning and refrigeration (HVACR) systems that are currently used in both residential and commercial applications. The 2020 American Innovation & Manufacturing (AIM) Act is bipartisan legislation that was signed into law. The AIM legislation empowers the Environmental Protection Agency (EPA) to reduce the production and consumption of hydroflourocarbons HFCs by 85 percent by the year 2035. (more…)
Hazard can be defined as a potential source of harm. Machine safeguarding seeks to protect people from these potential sources of harm. Often distance from a hazard will play a key role in providing a means of protection.
One would often think of distance as it relates to the location of a barrier guard from a hazard. ANSI B11.19, Performance Criteria for Safeguarding, defines safety distance as “the distance a safeguard is installed from a hazard such that individuals are not exposed to a hazard.” An example from ANSI B11.19 of the recommended distance of a slotted opening in a barrier guard from a hazard is shown in the table below:
Table 1: Minimum Slotted Opening vs Distance from Hazard – From ANSI B11.19
This information will help assess if the opening present in a barrier guard will meet the values established in a consensus standard such as ANSI B11.19. These distances and dimensions should be carefully considered when designing fixed barrier guards.
However, when more sophisticated means such as safeguarding devices are used to protect an individual from a hazard, distance takes on a different meaning. ANSI B11.19 defines a safeguarding device as “a device that detects or prevents inadvertent access to a hazard.”
A light curtain is a well-known presence-sensing device. ANSI B11.19 defines a presence sensing device as “a device that creates a sensing field, area or plane to detect the presence of an individual or an object.” An example of a light curtain is shown below.
If the individual utilizing a machine protected by the light curtain breaks the plane created by the sensing device, then the hazard behind must be rendered safe before it can be reached. For example, a hazardous motion must stop to prevent an injury to the individual that breaks the plane. Here the distances noted in Figure 1 above may not be applicable and a different method of determining the safety distance should be considered.
ANSI B11.19 states in section 6 General safeguarding requirements, 6.3 Safety distance:
“When required by this standard, the guard or safeguarding device shall be located a distance from its associated hazard such that individuals cannot reach the hazard before cessation of hazardous motion (or situation).”
Here we see that the hazard must be rendered safe before an individual can reach it through the presence sensing device and be injured.
Furthermore, section 8 Safeguarding devices, 8.3 Electro-optical, RF and area scanning presence-sensing safeguarding devices, 8.3.2.3 states:
“The presence sensing device shall be installed at a location so that the effective sensing field prevents individuals from reaching the hazard(s) during the hazardous portion of the machine cycle.
How do we determine this location or “safety distance”? Explanatory information in ANSI B11.19 notes:
“The safety distance calculation is dependent upon the:
Speed of approach of the individual
Total response time of the safeguarding device as stated by the supplier
Response time of the interface
Response time of the control system
Time it takes the machine to stop hazardous motion; and
Depth penetration factor of the safeguarding device.”
Here we see that with a presence sensing device, the value for a safe distance has many facets that must be considered to provide for safe operation by a user. ANSI B11.19, Annex D provides a method for determining what a safe distance should be based on factors mentioned above.
Safeguarding is often not a one size fits all activity. Careful consideration should be given to the safeguarding method chosen and proper attention paid to the specific design details. Careful selection and proper design details will lead to a safer machine.
Chad Jones, PE, CFEI, CVFI, CMSE has a Bachelor of Science in Mechanical Engineering from Clemson University. Chad has over 25 years of engineering experience including mechanical, process, and manufacturing engineering. This work has included equipment design, machine safeguarding, cost estimating and safety compliance. Chad also has over 10 years of commercial, industrial, and residential HVAC and plumbing design experience. A lifelong auto and motorcycle enthusiast, Chad is accomplished in the maintenance, repair, and modification of vehicles and engines. Chad is a Certified Fire and Explosion Investigator, Certified Vehicle Fire Investigator, and IFSAC certified Firefighter II in Greenwood County, South Carolina.
No kidding, I’m passionate about fire protection! To prove it, I could tell you stories about the damage I have seen from various failures from freezes to fire pump cooling to what happens when a fire hydrant’s weep holes are clogged…. But instead, I will tell you about smoke alarms!
Although it’s still new in my head, my home just turned 10 years old. The decade has seen the replacement of two household appliances and at least one HVAC repair… now what? A paint and décor refresh? Maybe, but that’s not what the fire protection engineer is thinking! It’s time to replace the smoke alarms! (more…)
When we step out onto the road as pedestrians, most of us assume that we are easily visible to oncoming drivers. However, research shows that pedestrians frequently overestimate their visibility, especially at night or in low-light conditions. This overconfidence can lead to dangerous situations, contributing to accidents and fatalities. Understanding why pedestrians overestimate their visibility is crucial for improving road safety and preventing accidents. (more…)
Trick-or-treating is a fun and festive activity, but it comes with certain hazards that can pose risks to children and even adults. In addition to vehicle and pedestrian collisions and accidents, tripping and falling while trick-or-treating is a common hazard, especially for children navigating unfamiliar and dimly lit areas at night.
Children and adults can face tripping hazards on walkways while trick-or-treating.
Tripping hazards can be mitigated through compliance with walkway safety standards such as ASTM F 1637-2021: Standard Practice for Safe Walking Surfaces. ASTM F1637 is a standard that provides (more…)
Trick-or-treating is a fun and festive activity, but it comes with certain hazards that can pose risks to children and even adults. In addition to trip and fall hazards while trick-or-treating, there is also an increased risk of vehicle/pedestrian collisions due to the increased pedestrian activity in the roadway at night.
Child trick or treating during Halloween in the roadway.
At night, there are two significant problems facing drivers that contribute to pedestrian/vehicle collisions: (more…)
What materials are suitable for installation in Heating, Ventilation, and Air Conditioning (HVAC) plenums? Let’s first define a plenum. The 2021 edition of the International Mechanical Code (IMC), a subset of the International Building Code (IBC), defines a plenum as “an enclosed portion of a building structure, other than the occupied space being conditioned, that is designed to allow air movement, and thereby serve as a part of an air distribution system.” (more…)
Fire protection is an expanse that I am both fascinated by and passionate about. To prove it, I could show you my sprinkler collection… the old ones, the new ones, the sizes, the features! But instead, I will share some information to show you the relationship between fire protection systems and other systems that you may have never thought about!
Fire protection, suppression, and alarm systems often do not act alone. They can be in cahoots with life safety systems or other equipment or building systems to mitigate fires and help firefighters. Many, but not all, of these functions are associated with fire alarm systems. Many, but not all, of these functions are customary and expected. Some of these functions will automatically reset when the alarm or system is reset, but not all! (more…)
Many sites that are protected by fire sprinklers will have at least some amount of private underground fire water piping. Its purpose is to make water available for fire protection or suppression at a needed flow and pressure. Its presence is usually quietly evidenced by the connected objects that occasionally surface along its course, like valves, fire department connections and private hydrants, termed appurtenances. Underground water piping commands attention, though, when (more…)
A proper collision scene documentation, lovingly referred to as a scene doc, will make or break the investigation… guaranteed! While not necessarily all inclusive, here are a few evidence collection / documentation techniques that have served me well over the years.
Some, if not most, collision scene evidence is short lived, and tire marks (more…)
