Amerex B402 Vs. B500 Fire Extinguishers: Which Is Better?

Fire extinguishers are an essential safety device for homes and businesses. They allow you to quickly put out small fires before they grow into an uncontrollable blaze. Choosing the right type of fire extinguisher for your needs is crucial. Two popular options are the Amerex B402 and B500 models. 

But what exactly sets these two extinguishers apart? This guide examines the key differences, pros and cons of Amerex B402 and B500 to help you determine which is better for your situation.

A Brief Comparison Table

Aspects	Amerex B402	Amerex B500
Agent capacity	4 lbs	10 lbs
Discharge time	9 sec	22 sec
Effective range	12-15 ft	12-15 ft
Fire class	Class B	Class B
UL rating	21B	21B
Filled weight	15 lbs	37 lbs
Height	18 in	24 in
Pros	Compact, portable, affordable	Increased capacity and discharge time
Cons	Limited capacity, frequent replacement	Bulkier, higher upfront cost
Best for	Minimum code, portable use, vehicles	Larger Class B fire potentials

Overview Of Amerex B402 And B500

Both the Amerex B402 and B500 are dry chemical extinguishers designed for suppressing Class B fires. This refers to fires involving flammable liquids such as grease, gasoline, oil, and paint. They work by coating the fuel source with a chemical powder, interrupting the chemical reaction of the fire tetrahedron.

The core difference lies in their size and capacity. The B402 contains 4 lbs of monoammonium phosphate-based fire suppressant. The B500 is larger, holding 10 lbs of the same dry chemical agent. Both extinguishers are UL rated for suppression of 21 sq ft fires. But the B500’s extra capacity allows for a longer discharge time.

Key specs comparison:

• Agent type – Monoammonium phosphate dry chemical
• Capacity
  • B402 – 4 lbs
  • B500 – 10 lbs
• Discharge time
  • B402 – 9 seconds
  • B500 – 22 seconds
• Effective range – 12-15 ft
• Fire class – Class B flammable liquids
• UL rating – 21B

Now let’s examine the advantages and limitations of each model in greater depth. This will give you a better feel for which Amerex extinguisher suits your particular fire protection needs.

Pros And Cons Of Amerex B402

Pros

• More compact and lightweight
• Lower cost upfront
• Easier to handle and aim
• Fits in more confined areas
• Meets minimum code for Class B fires

The B402 tips the scales at just over 15 lbs filled. Its smaller size makes it easier to manipulate and accurately direct the discharge stream. The light weight also makes the B402 more suitable for mounting. It can be installed in vehicles, on boats and RVS., and in other applications where having a portable extinguisher is desired.

The 4 lb capacity meets the minimum recommendations for suppressing 21B class fires. This compact extinguisher is affordably priced, giving you basic fire protection without a big investment.

Cons

• Limited firefighting capacity
• Short discharge time
• Requires early activation in fire situations
• May not fully extinguish larger flammable liquid fires
• Needs frequent replacement compared to larger models

With only 9 seconds of discharge time, the window of opportunity for suppressing a fire with the B402 is small. You must activate it during the incipient (beginning) stage before the fire grows in size and intensity. Flammable liquid fires can spread rapidly, potentially exceeding the extinguisher’s limited capacity.

The B402 will likely knock down a fire, but may not totally eliminate it. The short duration often requires follow-up application if the fuels reignites. More frequent replacement is also needed, as the 4 lb fill doesn’t last as long as larger 10 lb models.

Pros And Cons Of Amerex B500

Pros

• Longer discharge time
• Increased firefighting capacity
• More likely to fully extinguish larger flammable liquid fires
• Requires less frequent replacement
• UL rated for up to 21B class fires

With 22 seconds of discharge time, the B500 allows for a longer and more thorough application on threatening fires. The larger 10 lb capacity delivers more fire suppressant material to help fully extinguish, rather than just temporarily knock down, larger flammable liquid fires.

This added capacity results in a longer service life before needing refill or replacement. The B500 meets NFPA 10 recommendations for a minimum 10B:C rating, giving you extended protection for Class B hazards.

Cons

• Heavier and bulkier
• Potentially unwieldy
• Higher upfront cost
• Difficult to mount in some locations
• Overkill for minimum code requirements

The B500 tips the scales at just under 38 lbs filled. This makes it harder to manually handle and accurately aim at fires. The larger cylinder size also limits mounting options, as the extinguisher may be too big and heavy for some applications.

You’ll pay more upfront for the 10 lb capacity VS. 4 lb models. If all you need is the minimum required firefighting capacity for Class B hazards, the B500 may be overkill and not worth the added cost and size.

B402 Vs. B500 Fire Suppression Capabilities

To better gauge the firefighting potentials of each Amerex model, let’s compare how they perform in various simulated flammable liquid fire scenarios:

• Small grease fire (15 sq ft pan) – Both fully extinguish this size kitchen grease fire. The B500 provides longer suppressant discharge but isn’t necessary for a fire this small.
• Medium grill/RV fire (18 sq ft propane blaze) – The B402 knocks down and minimizes this size fire, but it could potentially re-ignite without total extinguishment. The B500 provides complete suppression for a fire of this magnitude.
• Large garage/shop fire (25 sq ft gasoline puddle) – The B402 can temporarily suppress but likely won’t fully put out a sizable flammable liquid fire like this. The B500 provides the best chance for complete fire elimination.
• Extra-large industrial fire (40 sq ft diesel fuel spill) – Neither extinguisher has the capacity to independently extinguish an extra-large flammable liquid fire that exceeds UL ratings. The B500 could help minimize spread or supplement automated systems until firefighters arrive.

As you can see, the B500’s extra capacity better equips it for handling medium-to-large Class B fires. But for smaller fires, the compact B402 may still get the job done.

Ease Of Use Comparison

When selecting a fire extinguisher, ease of operation is also important to consider:

• The B402 is fairly easy to wield and aim even for those not well-versed in fire extinguisher use. Its light 15 lb weight and compact cylinder make it simple to get into action quickly.
• The B500 is bulkier and heavier at 37 lbs filled. It takes more strength and dexterity to maneuver the larger extinguisher. But the added weight also makes it somewhat more stable for absorbing recoil during discharge.
• Both feature a squeeze-grip trigger valve for quick agent release. The B402 is slightly simpler to grip and squeeze accurately with one hand.
• Novice users may find the B402 easier to control. But the B500’s operation is not overly difficult for average adults with proper handling.
• Watching an instructional video ahead of time helps ensure you use either extinguisher properly when an emergency arises.

So while the B500 gives you more firefighting capacity, the B402 offers a bit more convenience for infrequent or novice users. Also watch this review!

Fire Codes And Recommended Class For Each Model

It helps to understand fire codes and classifications when selecting the right extinguisher. The NFPA 10 standard outlines recommendations based on types of fuels and potential fire hazards:

• The B402’s 4B:C rating meets the minimum NFPA 10 specification for Class B flammable liquid fires.
• The B500’s 10B:C rating provides an improved capacity according to NFPA 10 guidelines.

OSHA also mandates that fire extinguishers be compatible with the types of materials found in a workplace or facility.

What does this mean for each model?

• The B402 is suitable for minimum code compliance in applications such as offices, boats, RVS., and light commercial settings.
• The B500 fits environments with larger Class B fire potentials including warehouses, garages, machine shops, restaurants, production facilities, and similar.

Check your local fire codes for specifics on required ratings based on room size, building use, occupancy type, and fire hazard level. This will help determine if a 4B:C or 10B:C extinguisher is recommended.

Frequently Asked Questions (FAQ)

Conclusion

Amerex B402 and B500 fire extinguishers both utilize a monoammonium phosphate dry chemical agent tailored for Class B hazards. The key difference lies in capacity. The B402 is more compact and portable, while the B500 offers expanded firefighting capability.

For small facilities or applications needing only the minimum 4B:C rating, the budget-friendly B402 may suffice. But the B500’s 10B:C rating gives it an advantage for suppressing medium-to-large flammable liquid fires. Consider the size and types of hazards when choosing the Amerex extinguisher that’s right for your fire protection needs and objectives.