You are welcome to this guide. Do you seek to find out the origin of smoke detectors? You are at the right place. Knowing the history of any equipment is always important. Like every other tool, smoke detectors have an origin, that’s what we’ll discuss in this guide.
What is A Smoke Detector?
A smoke detector or smoke alarm is a device that detects smoke and issues an alarm to alert nearby people that there is a potential fire. A household smoke detector will typically be mounted in a disk-shaped plastic enclosure about 150 millimeters (mm) in diameter and 25mm thick, but the shape can vary by manufacturer.
Being an important aspect of fire safety, smoke detectors have been a major life-saving device by alerting people to the danger of fire.
Types of Smoke Detectors
- Optical detector
An optical detector is a light sensor. When used as a smoke detector it includes a light source (infrared LED), a lens to collimate the light into a beam, and a photodiode or other photoelectric sensor at right-angles to the beam as a light detector.
In the absence of smoke, the light passes in front of the detector in a straight line. When smoke enters the optical chamber into the path of the light beam, some light is scattered by the smoke particles, and some of the scattered light is detected by the sensor. Increased input of light into the sensor sets off the alarm.
Another type of optical detector works by using a straight line infra-red beam from the sender to the receiver. When smoke enters the beam, some light is scattered which results in less light detected by the receiver. A decreased input of light into the receiver sets off the alarm.
Also seen in large rooms, such as gymnasia and auditoria, are projected beam detectors. A unit on the wall sends out a beam, which is either received by a receiver or reflected via a mirror. When the beam is less visible to the “eye” of the sensor, it sends an alarm signal to the Fire alarm control panel.
Optical smoke detectors are quick in detecting slow-burning, smoky fires. They are less sensitive to false alarms from cooking and bathroom steam than are ionization smoke alarms.
- Ionization detector
This type of detector is cheaper than the optical detector, however, it is sometimes rejected for environmental reasons. It can detect particles of smoke that are too small to be visible. It includes a tiny mass of radioactive americium-241, which is a source of alpha radiation.
The radiation passes through an ionization chamber, which is an air-filled space between two electrodes and permits a small, constant current to flow between the electrodes. Any smoke that enters the chamber absorbs the alpha particles, which reduces the ionization and interrupts this flow of current, setting off the alarm.
What’s inside the detector?
Once Freymann and Tolman had discovered their fiber, it was relatively simple to build a part-electrical, part-mechanical smoke detector around it:
- A length of the magic fiber (yellow) is stretched around a wheel (red) inside a metal container (gray) with holes at the bottom through which smoke can enter.
- The fiber is attached to a pivoting lever (light blue), held in place by a spring (purple).
- The blue lever holds another pivoting lever (green) in place.
- The green lever supports an electrical contact (dark blue) and holds it well above a second identical contact.
- The two contacts connect to a battery-powered bell or another electrical alarm circuit (not shown).
Who invented smoke detectors?
Good question! Search online, and you’ll quickly find out that fire alarms were invented by US physicist and mathematician Francis Robbins Upton in 1890, while George Andrew Darby invented the first smoke detector in England in 1902. A more detailed search will tell you both of these “facts” are wrong.
According to the US Patent and Trademark Office database, Francis Upton and his partner Fernando Dibble filed the US Patent 436,961: Portable Electric Fire Alarm on March 24, 1890, and the patent was granted on September 23 the same year.
But that wasn’t the first fire alarm, because the USPTO also has on record US Patent 344,673: Automatic fire alarm and extinguisher by William Neracher of Cleveland, Ohio, filed on September 8, 1885, and patented on June 29, 1886—several years earlier than Upton and Dibble’s. Neracher’s alarm is entirely mechanical and works quite like a modern fire sprinkler.
The earliest smoke detector I can find on the US Patent and Trademark Office database is this one, patented by Oscar Freymann and Charles Tolman of Brooklyn, New York City, in December 1901 (and there might be even earlier ones). Surprisingly, for the early 20th century, it’s an electric detector, but it doesn’t use a photocell or ionization (those technologies are much more recent).
In 1915, people living in homes or apartments could expect that if their home caught fire, they’d have a one in ten chance of that fire killing them.
One hundred years later, the statistic has dropped to a one in one hundred chance of dying from a fire in your home or apartment. The key change agent in those statistics is without a doubt the invention of the practical, inexpensive home smoke alarm.
Smoke detectors have been around since the late 1880s. William Neracher patented the first heat and smoke detector on June 29, 1886. Thirty years later, Swiss physicist Walter Jaeger was working to invent a sensor for poison gas but was failing.
Sitting at his desk, he lit a cigarette and was startled to notice his “poison” device was responding to the smoke emitting from his coffin nail. His work translated into the road map for modern smoke detectors.
In 1939, another Swiss physicist Dr. Ernst Meli developed a device with an ionization chamber that could detect gasses in underground mines. He also invented a cold-cathode tube that could amplify the small electronic signal created by the detection mechanism to a strength sufficient to trigger an alarm. The result was the ionization smoke alarm.
The first ionization smoke detectors were extremely expensive. First introduced into the U.S. market in 1951, their use was limited to commercial and industrial facilities. There were various attempts at creating more practical devices, but as of 1963, were quite limited and did not have much public exposure.
Duane Pearsall is considered the “father of smoke detectors.” He and collaborator Stanley Bennett Peterson developed the first practical home smoke detector. It was called the “SmokeGard 700.” Made of fire-resistant steel, it was shaped like a beehive.
The key to the SmokeGard 700 was the removable and replaceable battery that made its operation cost-effective. Early studies in the 1960s demonstrated that smoke detectors responded to fire faster than heat detectors.
Stanley Peterson, who as an employee at Pearsall’s company, Statitrol Corporation, contributed to the evolution of smoke detectors by developing a widely copied plan for mass distribution. Even with these breakthroughs, the cost of individual alarms was still high, often reaching into the $200 + per unit range.
By 1972, ionization detectors were available with power coming from a standard 9-volt battery. The cost had dropped to just over $100 per unit, and they sold at a rate of approximately 200,000 units per year.
In 1974, Sears, Roebuck, and Company put its name on BRK brand battery-operated smoke alarms. It was during this time that major technological advances were made, and by 1975, the word was out: smoke detectors were saving lives in house fires.
Sales jumped to an estimated 8 million units in 1976, and up to 12 million units the following year. Several factors played into the increase in acceptance by the public, including solid-state circuitry, which made alarms more attractive, more effective sensing and alarm sounding, and the option of AA batteries in some models.
Development and distribution of smoke alarms were becoming competitive as contractors and home builders began including smoke alarms in their work. Statitrol sold its invention to Emerson Electric in 1980 and Sears retailers began selling the units nationwide with a, “now required in every home” campaign.
The first national standard for smoke detectors, now more commonly referred to as smoke alarms emerged in 1967. The National Fire Protection Association developed NFPA-74, which defined a standard by which smoke alarms could be used in the home.
Shortly thereafter, the AEC allowed individual homeowners to use smoke alarms without getting a license from their local building department.
As of November 2013, it is estimated that smoke alarms are installed in 96 percent of U.S. homes and 85 percent of UK homes. An amazing fact is that 30 percent of those alarms are estimated to not work, due to aging, removal of batteries, or failure of the homeowner to replace dead batteries.
Benefits of Smoke Detectors
Every smoke detector has one goal – to improve fire and smoke safety. The choices are endless but should be tailored to what works best for your home. You can buy a smoke detector as a standalone device or with a home security system.
Remember to always buy from a trusted manufacturer, and read all manuals before installment. For assistance with installing and understanding the smoke detector requirements contact your local fire department. Regardless of the options, smoke detectors aren’t optional when it comes to home safety. Here are the most common benefits.
- Faster smoke detection. The sooner the detector finds danger, the better. Extra seconds to safely evacuate the home could save you from inhaling life-threatening smoke and fumes. Remember to have a fire evacuation plan for a fast and safe exit if the alarm sounds.
- Cost-effective fire safety. Most smoke detectors cost less than $15 and can often be purchased in sets of two or more for better cost savings. Smoke detectors with smart technology can be more costly but come with added benefits such as mobile notifications of smoke, voice commands, and easy syncing to other home devices. For just a few bucks, you’ll have peace of mind while preparing your humble abode for the unthinkable.
- Easy monitoring. Smoke detector check-ups are often quick and easy. It’s as simple as setting a monthly reminder to vacuum the detector free of dust and changing the batteries annually. Even during weather preparedness, most smoke alarms include backup batteries to continue monitoring during power outages. These regular routines keep the home ready for the first sign of trouble.
Knowing the history of smoke detectors, you are at a better place to value it. We have tried as much as possible to simplify the details on the history of smoke detectors. We hope we helped to clarify your doubts about the history of smoke detectors.