There are a few important things to consider when selecting the right handheld particle counter for your needs. Handheld particle counters are commonly use for spot checking cleanrooms, cleanhoods, filter testing, general indoor air quality testing and other applications where portability and a low cost is essential.
IMPORTANT NOTE:
Handheld particle counters have .1 CFM flow rate and are not designed for certifying cleanrooms.
Several different handheld particle counters are available that offer ease of portability and battery operation for use “on the road.” Unless you plan on manually loggin your data on a clip board, select a unit that offers internal memory. Many handheld particle counters only count one size particle at a time and must be switched to a different size each time you want to monitor a different size. Some handheld particle counters offer simultaniuos counting of several chanels.

The Lighthouse 3016 ($3,495 at time of writing) offers a graphic touch screen interface, counts 6 particle size chanels at once along with temperature, relative humidity and stores each record in it’s class leading internal memory along with a time and date stamp for each record. The Lighthouse 3016 handheld particle counter also offers an easy method to download the data to your PC and includes free software to transfer the data into an excel spreadsheet.

If you find that you do not have a use for internal memory or counting multiple sizes, lower cost units, such as the MetOne GT-321 can give you accurate particle counts which display on a simple LED screen and a low sticker cost of well under $2000

Last year we picked up a new line on gas monitors that are manufactured by Crowcon Detection Instruments Ltd., based in Abingdon, Oxfordshire in the UK. We reviewed several different gas monitors and companies that offer products for gas monitoring and chose Crowcon for several reasons.

Crowcon is not very well known in the U.S. though they are very popular abroad. We found that they have an excellent product selection, great value and several features missing from the gas monitors that are popular here in the U.S. as well as a commitment to expand their U.S. market.

In our first meeting with them last summer, Drew Saunders (Crowcon S.E. U.S. Sales Manager) came out to visit and brought along an impressive product line and spent the day training our staff and showing off their product line. While the Crowcon powerpoint presentation was clearly geared toward the U.K. market, we learned a lot that day and got some hands-on experience with several of the units including the Crowcon Tetra, Gasman and Eikon personal gas monitors. Since that day I’ve been impressed with the level of expertise and service that our reps at Crowcon have provided.

Sometimes we pick up a product that is truly “best in class” as we have here with the feature packed Crowcon Tetra. What is surprising to me is that customers are continuing to pay more money for other products that don’t have the features and benefits that the Tetra offers. Beside having a lower price, the Tetra is also the easiest to use multi-gas monitor on the market, offering true one button operation. We’ve put together a gas monitor comparison chart that stacks the Tetra up against the most popular gas monitors available today.

If you are in the market for personal gas monitors, you should take a look; I think you’ll be impressed.

Second hand smoke consists of a toxic blend of particles, gasses and odors. Generally, smoke eaters fall into two main categories, electrostatic or media based. Some newer hybrid smoke eaters combine technologies in an effort to offer features, convenience and benefits from both smoke eater groups.

Electrostatic smoke eaters usually consist of a prefilter, to remove large particles, an ionizing section and a cell containing several electrostatic collector plates. When second hand smoke is brought into the system, the prefilter removes that large particles of smoke, dust and other contaminates. Next, the second hand smoke passes through the ionizing section, which charges the smoke particles in the air. The charged particles then pass through the electronic cell, where the smoke particles magnetically stick to the collector plates. Some hybrid smoke eaters also include a carbon post filter section, which helps to remove gasses and remove smoke odor.

Media based smoke removal systems consist of a prefilter, a main filter and usually a carbon post filter. These smoke filters work together to remove smoke particles and to remove smoke smell. Media filters, such as HEPA, are made of tightly woven fabric, which traps the smoke particles, removing them from the airstream. Gas phase media is usually granulated carbon, or a specialized carbon blend. Potassium iodide or potassium permanganate is often used to treat carbon. Activated carbon contains thousands of tiny pores which trap gasses and smoke odors through a process called “adsorption.” Potassium additives oxidize gaseous contaminants and combine with carbon to provide superior smoke odor removal.

There are a few things to keep in mind when selecting the right smoke removal system for your needs. Some smoke eaters claim to have carbon post filters, when in fact they use a foam pad with carbon dust sprinkled onto it which has very little effect in removing toxic gasses or odors. Always look for a unit that has several pounds of granulated carbon if you want to effectively remove smoke odor.

Pros and Cons of Different Smoke Eater Technologies

There are benefits to each kind of smoke eater, when choosing a smoke removal system you should select a system that best suits your needs and budget. Electrostatic smoke eaters use a washable filter as the main filter in the smoke removal system. This filter does not need to be replaced, but it does need to be cleaned regularly. Washable electronic filter cells offer considerable long term savings, but they do require some labor.

Another benefit in using a smoke eater that utilizes an electronic filter cell is that, unlike media filters, they do not decrease the airflow as they load. The benefit of not restricting airflow means that the unit will provide the same coverage area, even when the filters are dirty. The same cannot be said for media filters, which lose as much as 50% of their airflow, when the filters are only halfway through their lifespan.

Media based smoke eaters use a replaceable smoke filter, which do not require regular maintenance, but the smoke filter does require replacement about once per year. Media smoke filter replacements usually cost around $200 or more. Any smoke removal system with carbon must have the carbon replaced periodically if it is to remove smoke smell.

Other Smoke Removal Technologies

In recent years there have been a number of companies claiming to have found the next great smoke removal system. It is important to understand what these technologies are, how they work and what other effects they have, or may cause.

Ozone Generators

Many new products on the market that claim to be smoke removal systems use ozone. Ozone is a powerful cleaning agent and is capable of odor removal. Ozone is not a smoke filter and does not remove smoke particles. There are many companies on the internet touting their ozone producing machines as a smoke eater or a smoke odor eliminator. It is important to know that ozone has been proven to be harmful to humans and may pose a potential health hazard.

Ozone producing units are more suited to restoration work and should not be used in occupied spaces. While some manufacturers claim that their units only emit a “safe level” of ozone, the fact is, almost all units exceed this specification. What is deemed a safe level is not nearly enough ozone for it to be effective as an air cleaner or “smoke odor eliminator.” Furthermore, ozone levels are measured in “parts per million” and in order for a claim of a “safe level” one would need to know the total volume of air in the area in the area in which the unit is to be used.

Ionizers and Ionic Air Cleaners

Ionization is the process that charges the particles in the air with an electric polarity. When these charged particles come into contact with other items, they cling to the surface. Electrostatic smoke eaters have an ionizing section followed by a series of collector plates to capture the smoke particles.

Most ionic air cleaners, claiming to be smoke eaters or smoke removal systems, use only an ionizing section. These ionizers emit the air with the charged particles; the particles adhere to anything with which they come into contact. This commonly includes walls, clothing, furnishings and even the interior of your mouth and lungs. Some ionizers will have only 1 or 2 collector plates which are not really enough to effectively handle smoke removal and are more intended to reduce household dust.

Coverage area of a smoke removal system is the most common area where people are confused. Manufacturers and marketers of smoke removal systems contribute to this confusion by overstating the coverage area for their smoke eaters. As an indoor airquality specialist, this is the area where I am most helpful to my clients. While calculating the coverage area of smoke eaters is not an exact science, we are going to share with you some of the rules that we use everyday, when designing and configuring systems for our clients, which include many popular bars, restaurants, casinos, bowling alleys, bingo halls and our favorite… night clubs!

There are several factors to consider when sizing a smoke removal system:

1. Air changes per hour

2. Obstructions

3. Number of people / number of smokers

Air Changes per Hour

We usually try to meet or exceed 12 air changes per hour in most smoking applications. If you are trying to eliminate cigar smoke or if you are dealing with secondhand smoke, you should try to achieve 14 (or more) air changes per hour. To calculate airchanges per hour, you will need the measurements of the room or area you intend to cover and use the following equation:

In the below example, we will use a 2500 square foot room, with 9 foot ceilings and we will try to achieve 12 air changes per hour.

1. Square footage X ceiling height = cubic feet of air

example: 2500 square feet X 9 foot ceilings = 22,500 cubic feet of air

2. Cubic feet of air / 60 (minutes per hour) = CFM required for one air change

example: 22,500 cubic feet / 60 = 375

3. Multiply - CFM required for one air change X the number of air changes required = CFM needed

example: 375 X 12 = 4500
 

Estimating air change per hour:

No smoking =  6-8 air changes per hour

Light Smoking = 10-12 air changes per hour

Moderate Smoking = 12-14 air changes per hour

Heavy smoking = 16+ air changes per hour
 

In the above example we would need 4500 total CFM to effectively remove the smoke from our 2500 square foot room. In this case we would recommend 4 units that each have about 1100-1200 CFM.

A few things to consider…

If you are using media based smoke eaters remember that as the smoke filters load (become dirty), they restrict airflow. A smoke eater that has 1,000 CFM will only deliver about 600 CFM when the filters are half-way loaded. When sizing media based smoke removal systems, it is best to oversizethem by about 30-40% to make sure that they will still be effective once the smoke filters start to become dirty. Electrostatic smokeeaters do not restrict airflow when they become dirty, but if you add carbon post filters, you should oversize the units by about 10-15% to account for the airflow restriction caused by the extra carbon.

Obstructions

Calculating airchanges per hour is a good indicator of the size of the smoke removal system you will need, or the number of smoke eaters you will need to effectively remove second hand smoke, but it is not the only thing to consider. Remember that a smoke eater relies on airflow and cannot work around corners, through walls or through doorways or archways. In our above example we used a 2500 square foot room and we decided that 4smoke eaters would provide good coverage. If this 2500 square foot areais broken up into several smaller rooms or separated areas, four 1200CFM smoke eaters would not be the best choice. If we are dealing withseveral smaller rooms, it would be best to size each room and choose asmoke eater for each room that can achieve your target air changes perhour.

Number of people/smokers

When designing or sizing a smoke removal system another factor to consider is the maximum number of people and the number of smokers in the area you are expecting. A large smoke eater (1250 CFM) is suitable for about 30 people, with 10 of them being smokers. In our above example where we have calculated air changes per hour in a large room, the four units would be effective if we were expecting a maximum of about 100 peoplewith about 50 of them being smokers. If you expect more people, or more smokers, you should allow for more smoke eaters, more air changes per hour and therefore more CFM and more units.

The above examples and tips should help you determine how many smoke eaters you will need to effectively remove second hand smoke. There are other factors to consider, but if you follow the examples above, you should have an effective smoke removal system.

This post starts off the fume extraction section of this blog.