What’s the Difference Between a Bump Test and Calibration—and Why Should You Care?

If you work with direct-reading portable gas monitors (DRPGMs) to check oxygen levels and look for toxic or combustible gases, you’re likely familiar with the concepts of bump testing and calibration. But if you were given an on-the-spot pop quiz on the subject, could you tell the difference between these terms?

The main difference between a bump test and calibration is that a bump test determines whether a DRPGM can detect if a possibly hazardous gas is present, while calibration checks that equipment is accurate.

But it’s a little more complicated than that, and getting to know more about bump tests, the two types of calibration, and related best practices can help you keep these distinctions top of mind—and use them correctly.

Defining Differences

Direct-reading portable gas monitors fall under the responsibilities of safety equipment trade organization the International Safety Equipment Association (ISEA), which released a 2010 statement to improve consistency in how people use, test, and maintain DRPGMs. In that statement, the organization was careful to flesh out the differences between a bump test, calibration check, and full calibration as well as advise how and when to test with each method.

So What’s a Bump Test?

The ISEA defines a bump test as a

“qualitative function check where a challenge gas is passed over the sensor(s) at a concentration and exposure time sufficient to activate all alarm indicators to present at least their lower alarm setting. […] This is typically dependent on the response time of the sensor(s) or a minimum level of response achieved, such as 80% of gas concentration applied.”

This checks whether sensors and alarms are working as intended, and failure might indicate that a blockage is present. In sum, bump testing assesses function, not accuracy.

How Is Calibration Different?

Part of the confusion surrounding bump testing versus calibration lies in the fact that calibration checks and full calibration are two different things. Both of these types of calibration can test a DRPGM’s accuracy, but they’re used in different circumstances.

A calibration check, according to the ISEA, is a

“quantitative test utilizing a known traceable concentration of test gas to demonstrate that the sensor(s) and alarms respond to the gas within manufacturer’s acceptable limits.”

Calibration checks start by “zeroing” a DRPGM (resetting it to a reference point determined by the manufacturer) and testing that alarms go off after applying a high enough concentration of test gas. The resulting sensor reading should match the concentration listed on the test gas container. The ISEA says that a device is accurate within an acceptable range that’s “typically ±10-20% of the test gas concentration applied unless otherwise specified by the manufacturer, internal company policy, or a regulatory agency.”

The ISEA guideline describes full calibration as

“[t]he adjustment of the sensor(s) response to match the desired value compared to a known traceable concentration of test gas.”

This adjustment accounts for naturally occurring drifting and other environmental factors. Specially trained, qualified personnel are the only people permitted to perform full calibrations.

Bump Up Your Bump Test Knowledge and Avoid Calibration Frustration

Now that you know the differences in definition, let’s take a look at some tips and tricks for using both bump tests and calibration.

When to Test

Perform a bump test and calibration check every single day before anyone uses the DRPGM that day (and according to manufacturer’s instructions).

The DRPGM’s manufacturer’s guidelines—plus internal policies and regulatory recommendations—determine exactly how and how often to fully calibrate that particular DRPGM. Full calibration is also necessary if a bump test or calibration check fails. You can perform a full calibration twice, but after two “fails,” the device must be pulled from use. Full calibrations should also take place after the following types of exposures:

  • Different operator or working environment
  • Extreme environmental, storage, and operating conditions
  • Highly concentrated target gases and vapors
  • Solvent vapors and corrosive gases
  • Poisons and inhibitors

Testing Best Practices

When testing a device, use the following guidelines:

  • Perform the calibration in fresh air
  • Choose a test environment with conditions that match your workplace
  • Use a recommended gas mixture, which should meet the National Institute of Standards and Technology (NIST)
  • Check the gas’s expiration date
  • Always refer to your product manual for specifics

Keep a Record

It’s essential that you keep records of all device testing and maintenance. Should a user experience a reportable event with one of your devices, the Occupational Safety and Health Administration (OSHA) needs to see a history of all bumps and calibrations during the year prior to the incident. But even without an incident, testing and maintenance data can track other valuable information, and new technology makes record-keeping easier and more valuable than ever.

Digital tracking and remote monitoring are just some newer technologies that automatically track and allow you to manage your fleet’s bump tests and calibrations from wherever you are. Some can even be paired with GPS devices so that you always know where your workers are. If you detect that they’ve been exposed or if a man-down alarm indicates that a worker experienced a health emergency, you know exactly where to send help—and what kind of help to send.

Interested in simplifying the management of your gas detection fleet with automated calibration? Learn more about the MSA GALAXY® GX2 Automated Test System here.

Confined Space Rescue: What You Need to Know
Planning is bringing the future into the present so that you can do something about it now. - Alan Lakein, Bestselling Author and Time Management Expert

Unfortunately, it’s true—confined spaces can be dangerous. Asphyxiation, falls, entanglements, and other hazards could harm workers who must enter such places. No one wants to hear the words, “They’re unresponsive!” or “The gas detector’s alarm has gone off!” but the fact of the matter is that mishaps can and do happen. Often, rescuers are injured as well as workers. So when an accident occurs and workers need help, you don’t want to be caught by surprise… you want to be ready.

Readiness isn’t just being available to help at a moment’s notice. It also means preparedness—having a well-thought-out, well-practiced plan in place long before anyone enters a confined space. Not surprisingly, if you’ve determined your site meets the qualifications for a permit-required confined space, OSHA requires that you develop and implement a comprehensive system to deal with any emergencies which may arise.

Below are some of the necessary elements of a sound ready-to-rescue plan:

Must Do: Evaluate your site with rescue in mind

Planning for confined space emergencies begins with assessing your site’s unique situation. You’ve already considered what your workers need to perform their jobs; now you want to take into consideration what it would take to get them out safely.

Ask these questions to help determine the type of rescue that may be needed:

  1. Can a worker exit the danger zone without assistance?
  2. Alternatively, if there is a potential issue, can an attendant retrieve the worker without entering the confined space?
  3. Or does your scenario require an efficient, thoroughly trained rescue team, either on call or on site?

Must Do: Calculate response time and rescue time

We’ll assume you’ve decided your particular circumstances require a rescue team. A critical criterion for selecting your team is the length of time it will take them to respond to an emergency and evacuate the worker. OSHA states that rescuers should “respond to a rescue summons in a timely manner, considering the hazard(s) identified.”1

Michael Roop, CSP, an experienced rescue team trainer, advises calculating rescue team response time with a simple formula:

Response Time = Reaction Time + Contact Time + Travel Time + Assessment Time + Prep Time

Equation for response time

How long will it take to recognize that the worker may need assistance? How long will it take to inform the rescue team? How long will it take the team to arrive? How long will the team need to strategize the rescue and set up equipment?

Roop’s formula for rescue time is as follows:

Rescue Time = Time to Reach + Treat + Package + Evacuate the Victim

Equation for rescue time

According to Roop, the whole rescue process “can take approximately forty-five minutes to an hour.” A trained team, he adds, should be able to accomplish the rescue in less than an hour.

To learn more about rescue readiness—including response and rescue time—check out this webinar.

Must Do: Evaluate your prospective team

There are many more concerns to be addressed when selecting your rescue team. OSHA provides helpful criteria in 1910.146 App F, a non-mandatory appendix listing detailed questions useful for both an initial and a performance evaluation. Considerations include:

  • How will rescuers communicate with you, each other, and the worker?
  • Do rescuers have the necessary skills and equipment to meet your specific situation?
  • Are they authorized to respond immediately?
  • Who is in charge?

Must Do: Once You’ve Designated Your Rescue Team, Practice!

It goes without saying that practice can make the difference between chaotic, costly mistakes and calm, effective performance. Training for confined space rescue means—among other things—knowing how to use equipment and understanding potential complications.

Training doesn’t stop with head knowledge, however; it also involves simulated rescue drills, both planned and surprise. OSHA requires that your team practices rescue operations once per year using dummies, manikins, or real people in representative spaces.2 Additionally, you must physically evaluate your team’s performance. “Test them,” advises Roop, “so you know you have a top-notch team.”

In sum, it’s the employer’s responsibility to ensure that workers in confined spaces can count on the quickest, most competent rescue attempt possible should things go wrong. It’s not enough for your rescue team to have good-looking PPE and nice-sounding promises—on the contrary, you should vet your team with regard to both qualifications and capabilities. Then, should an emergency occur, you’ll be ready to rescue!

1: OSHA 1910.146(k)(1)(i)

2: OSHA 1910.146(k)(2)(iv)

Utility Safety: Three Major Mistakes to Avoid

Vigilance: “The careful watch for danger or difficulty.”

Almost nowhere is vigilance more important than within the nation’s utility industry. Hazardous working conditions include—but are not limited to—working at height, exposure to high voltage electricity, and confined spaces. Utility company employees who face these challenges, whether occasionally or routinely, can never let down their guard when it comes to their health and safety.

For utility safety managers, vigilance means not just knowing the dangers, but preparing for them, too; a manager must keep an eye on both the overall safety plan and its day-to-day implementation. With that in mind, here are three serious oversights that will threaten the effectiveness of a safety program.

Generalizing or downplaying the dangers of the job.

What safety manager doesn’t know both the unique and inherent dangers of the work? Sometimes though, often through no fault of their own, the safety manager’s focus shifts from striving for and achieving safety excellence to sorting through and keeping up with confusing standards and changing rules.

Of course, OSHA compliance is both sensible and necessary for a “legal” work environment. However, the best practices don’t stop there. A wise safety manager not only understands the general danger and meets basic standards, but considers each risk individually and provides custom safety solutions tailored to the worker and the job at hand. This policy, in turn, cultivates a safety-focused workplace culture, where workers master proper safety protocols and learn how to become their own safety advocates.

Not using the right PPE for the job.

Putting a utility worker in the wrong personal protective equipment (PPE) isn’t just a superficial oversight—it’s a potentially harmful or possibly even life-threatening error.

Especially in the utility industry, there are far too many hazards—known and unknown—to take a casual approach to selecting PPE. Three of the most common risks are:

  • Working alone with nobody to see or hear when help is needed
  • Being exposed to high voltage environments
  • Doing the job on a ladder or in a bucket at height

With these kinds of dangers, it’s important to choose PPE with care. Selection criteria include:

  • Is the PPE designed to protect against specific hazards workers may encounter, such as falls from height, arc flash, or foreign objects entering the eye?
  • Does the PPE meet the appropriate ANSI standards?
  • Does the PPE fit well, and is it reasonably comfortable to wear?

Not taking advantage of PPE innovations.

It’s difficult to keep up with rapidly changing technologies, let alone stay ahead of the innovation curve. That being said, utilities cannot afford to lag behind when it comes to PPE improvements or they risk missing out on opportunities to amplify their safety initiatives.

This doesn’t have to be an all-or-nothing proposition, though. There is middle ground: a PPE Acquisition Strategy. Simply put, a PPE Acquisition Strategy is a straightforward plan for when and how to invest in new PPE; when and how to get rid of unreliable, inappropriate, or outmoded PPE; and when and how to stay the current course.

One of the responsibilities of the utility safety manager is to continually look for new and better ways to manage safety. But even with heightened awareness and added attention to the hazards and innovations of the industry, there’s no guarantee an accident won’t happen. However, avoiding the mistakes outlined above tips the scale in favor of keeping electric, natural gas, telecom, steam, water and wastewater workers safer. And that, everyone can agree, is the right move.

Inspecting Your Safety Harness Part II: How to Read a Harness Label

These days labels are everywhere: on food, clothing, gadgets, and more. Shake Well Before Using. Tumble Dry Low. WARNING: Do Not Immerse in Water!

Designed to communicate an important message clearly and concisely, most labels do just that—although we’ve all seen humorous label fails! (One real-life example: a potato chip package label that read YOU COULD BE A WINNER! NO PURCHASE NECESSARY. DETAILS INSIDE.)

But it’s no secret that, in many cases, following product instructions can mean the difference between health and injury—or even between life and death. That’s why understanding a label’s message is really no laughing matter.

All workers using fall protection products need important information at their fingertips. To that end, you’ll find what looks like a little booklet sewn neatly into every MSA fall protection harness—out of the way, but quickly accessible. Of course, the label does not contain comprehensive information about the product; the product manual is the user’s most important resource. But the data on the label satisfies standards requirements and can be useful in other ways. Below, we’ll take a closer look at what a harness label says and what it means.

ANSI Standard

ANSI-rated harnesses are required to display the standard on the label booklet’s first page in large, bold letters: ANSI Z359.11-2014. The harness’s weight capacity—test-certified in accordance with that standard (typically 130–310 lbs.)—appears below the standard. Such prominent placement makes it easy for workers and safety managers to confirm this important information at a glance.

Data Card

The data card follows the ANSI standards page. Here you’ll find specifics for the harness part number, provided in English/Spanish/French:

  • Product Name and Model Number
    Material/Size/Style (Style typically refers to configuration of the chest strap)
  • Date of Manufacture
  • Serial Number (unique to the individual harness)
  • Class (designated by letter—more about this below)
  • Meets Standards: If applicable, the CSA standard is specified, accompanied by CSA logo. OSHA requirements are also referenced.
What are Some Practical Ways to Use Data Card Information?

1. You can track an individual harness by recording its model number, serial number, and date of manufacture as shown on the data card. Elsewhere on the label you will find a USER ID box, where, if desired, you may add your own identification number/name.

2. The information on the data card allows you to identify exactly what type of harness you have. Your harness’s name may indicate that it’s been designed for a specific function, such as the EVOTECH® Tower Harness or the Gravity® Welder Harness. Additionally, if you follow Canadian standards, you can double-check that your harness’s Class designation matches the task at hand. For example, if you will be working in a confined space, you’ll need a Class E harness.

3. The harness size and style recorded on the data card will help you select the appropriate harness for a specific user.

Class Designation

CSA Standards require that each harness is identified by a Class letter, which specifies connection points and application. As mentioned above, this information appears on the data card. At the end of the label booklet, you’ll also find icons to help you remember what each Class means:
A = Fall arrest
D = Suspension and controlled descent
E = Limited access
L = Ladder climbing
P = Worker position


It’s vitally important to take the warnings on the harness label seriously—you just can’t be too careful in situations where improper use of your gear could severely injure you or even take your life! Make sure you actually read the user manual and really do follow its instructions.


Capacity means the combined weight of the worker’s body, clothing, and tools. A harness may be rated to a larger capacity (e.g., 400 lbs.) for OSHA and CSA standards, but to meet the ANSI standard, capacity must conform to the ANSI limits shown in large type on the label’s first page (e.g., 310 lbs.).

Inspection Grid

For your convenience, MSA supplies a five-year grid where you can record when you’ve inspected your harness.

While much of what we’ve looked at above may seem obvious, that’s by design. The whole point of your fall protection harness’s label is to provide you with straightforward data you can access easily, so you don’t have to guess what kind of harness you have or if it conforms to the proper standards. After all—when it comes to your safety—there’s no such thing as TMI (Too Much Information)!

For comprehensive information about using MSA harnesses, read your harness’s user manual or call MSA Customer Service at 1-800-MSA-2222.