Testing and Selecting a Hand Held Metal Detector

How do you select a Hand Held Metal Detector?

https://www.academia.edu/18434912/Testing_and_selecting_a_security_hand_held_metal_detector

I have been working in the security field for a very long time and have been entrenched in the procurement and testing process for screening equipment. Trying to pick the right piece of equipment can be a very challenging process and without testing you really have no idea what you are getting. With expensive equipment like x-rays and walk through metal detectors most people do the research (or try) before they make a purchase. However when it comes to hand held metal detectors there is typically little or no research/ testing before they make a purchase. You will find claims from the vendors that their unit can detect specific threats but it is always best to test before you buy. This article is about how you can evaluate a hand wand and make a solid decision on what to purchase.

The very first thing you need to know about hand helds is that they will only detect something if the walk through metal detector alarms and your officers use the hand wand to test a person. Let me be very clear when I tell you that whatever you do not want getting into your building your walk through metal detector MUST be able to alarm to this threat. If the walk through does not alarm your officers will never use the hand wand and that threat is coming into your building.

When selecting a hand held metal detector you need to make sure that what you are buying is going to work. The only way to do this is to test the units and compare them and see how well each unit performs. The next factor that typically plays a large role in any procurement is the cost of the hand held. Prices can run from $20.00 to $300.00 dollars depending on the manufacture. Contracting officers are relying on the program manager (you) to provide them a GOOD technical evaluation. If you do not conduct a technical evaluation and only select based on technical specifications you are going to end up with the lowest bidder. So let’s try and explain how you can conduct testing for hand wands and provide a very comprehensive technical evaluation that will ensure you get the best product.

Step 1: Develop a test plan:

This is the key to making sure you figure out what each unit can and cannot accomplish. By testing the units with real test objects you can verify that the unit will work for what you are trying to prevent from coming into your building. All of these test objects you can typically get off the shelf for the testing and you potentially already have a large collection of test objects that you might have confiscated. At the U.S. Marshals we would collect buckets of these items each month so we had a ton of threats objects to pick from when we did our testing.

Edged weapon threats 3 inches and smaller Collected at a federal Courthouse

There is a standard out there for testing hand held metal detectors and it is put out by the National Institute of Justice (NIJ) and it was written in 2003. https://www.ncjrs.gov/pdffiles1/nij/200330.pdf

I am going to be very honest with you that this NIJ standard is something that cannot be done in the field and you need engineers and a lab to do the test (not going to happen). The NIJ standard also wants you to MAKE the test objects and this is by far the most ridiculous part of the standard. Everything they want you to test is an off the shelf item and trying to make these things is just not logical. I have even tested the NIJ test objects vs the real threats and I found many problems with how they perform.

1. The metallic mass is larger than an off the shelf like items and typically have a larger signal or distance they alarm. This means if you try and use them as a standard your baseline for the distance these threats alarm will be higher then what it actually is vs real threats. Best way to explain this is the NIG 3” stainless steel knife will alarm much farther away than a 3 inch plastic handle pocket knife. I typically found the distances were greater from about .5 to 1 inch when compared to real threat items.
2. The NIJ Standard only tests 3 inch knife blades and this could create a gap in your security for smaller knives. Add the above issue in number 1 with this and your security and detection becomes even more suspect.
3. The NIJ Standard have no test objects for IED’s and this is very disturbing as the IED threat is very hard to detect and the worst threat you can encounter. They really need to correct this but until they do it is a very serious problem with the standard
4. The test objects they suggest cost about $1,200.00 in the complete kit and I do not see a sheriffs Dept. department spending that kind of money to test hand wands. This fact alone makes the standard non usable and completely not effective.
5. The entire NIJ standard is VERY Prison centric and several of the test objects are a prison only threats. They should be separated out as “Prison only” test objects and not included with the rest. What a prison is looking for IS NOT what a county courthouse is looking for. The glaring test object is the aluminum blade which is a prison type threat as you cannot buy a pocket knife with an aluminum knife. I have searched google and could not find a single aluminum blade (only handles)
6. The worst part of the NIJ standards is they condone trying to discriminate a threat from a non-threat. This has NOT and will NOT ever work and is one of the biggest false hoods about metal detection. You CANNOT tell a metal detector to only alarm to threats and the ONLY thing you are doing is lower a zones sensitivity (trying to not detect belts, keys, etc.) and opening yourself up to a threat getting in.

The 3 inch knife length NIJ uses appears to be based on a Federal Law and you can find references to the requirement in a guide that is put out by the Department of Homeland Security (Prohibited Items in Federal Buildings).https://www.dhs.gov/sites/default/files/publications/ISC-%20Items%20Prohibited%20from%20Federal%20Facilities-%20An%20ISC%20Standard.pdf

“Dangerous Weapons: A weapon, device, instrument, material, or substance (animate or inanimate) that is used for, or is readily capable of, causing death or serious bodily injury, except that such term does not include a pocket knife with a blade of less than 2 1/2 inches in length”

I am not really sure how to say this in a nice way but I know for a fact that anybody I know who runs security does not let anything in the building that is sharp and pointy. So unless you are allowing knives into your facility that are under 2.5 inches in length you need to test pocket knives that have blades shorter than a 3 inches. I am pretty sure a knife under 2.5 inches can do some very serious bodily injury and if you allow that in your facility are taking a huge risk (sorry NIJ guys). I am sure it meant well when it was written but is not something that the average Security Supervisor can accomplish nor are the test objects accurate and up to date.

What you need is to break your test objects down into 3 categories (Large, Medium, and Small) like the NIJ has recommended but use items to test that are more realistic and relevant. The below is a list of items we suggest you can use to do a very good measurement of a hand wands capability:

Large ITEMS: Gun Threats or large metal threats

Large hand held metal detector threat items you should have no problem detecting with any hand wand. The distance away from the test object you will get an alarm will typically be much farther away than the smaller threats Items (3-8 inches). The distance is not as important as the fact that the hand held alarms to the threat. Distance is really only an issue if you have to touch the person to detect the object. Ideally your procedures should indicate that when you hand wand a person that you get a close to the person’s body as possible without touching them. A threat object is going to be right up next to their body so you have to get close to the person’s body and avoid following the contour of the clothing (will push you farther away). The closer you get to the person’s body the better your % of detection plan and simple. I have seen this time and again when I have done training at the Federal Law Enforcement Training Center (FLETC). Officers that are hand wanding 2 or more inches away from a person’s body WILL MISS threats.

1. Rebar 3/8”

3/8 inch rebar to verify at what distance the hand wand will alarm to the rebar in the floor (most building foundations use 3/8 inch rebar). I see this all the time that an Officer will be wanding down a person’s leg and once they get below the knee they get an alarm. The Officer starts trying to figure out what is causing the alarm. 9 times out of 10 it is the floor so having a hand wand that will NOT alarm near the floor is ideal. I will tell you that this capability is going to cost more so you may just need to alter your screening procedures and have them raise their leg when hand wanding. You can purchase up 12-18 inch cut pieces of 3/8 rebar at Lowes or home depot for a very low cost. The depth the rebar is buried in the concrete varies depending on how thick the slab is. The lowest number I have been able to find is around 1 inch. The means when you test the distance the hand wand alarms to the rebar add 1 inch to compensate for the rebar distance in the concrete.

The best test you can do is at the location you are doing hand wand screening. Test at what point the hand wand will alarm to the floor. Once you verify this distance you need to update your post orders and training so you officers know when they are get a alarm from the floor and not confuse it for a item hidden in a persons leg. A pat down or having them raise their leg is the only proper way to compensate for rebar in the floor causing alarms.

1. 380 semiautomatic pistol

Small 380 style firearm (very common weapon and the type most confiscated by TSA). If you are going to test a gun you should test what is common and small is size. The small 380 semiautomatic is a perfect weapon to test. Do the test with the mag in and out and you should have the mag fully loaded when testing. If you do not have access to real guns contact me and I have some test guns that are perfect and INERT that are very affordable.

2. Derringer .32 2 shot pistol

A derringer .32 pistol is the perfect hand gun to test as it is one of the smallest guns on the market. They also use the derringer 32 in a disassembled configuration as a test piece for a walk thru metal detector. If you do not have a real derringer I can get you an INERT test gun (contact me for more info). The Derringer is not a very common gun but if you want to ensure that you can detect a gun you want to test the smallest gun on the market.

3. Collapsible steel baton

A Baton with a total length of 16 inches or less is another real world threat object you can use for your testing. This is another very good large item to test and could potentially do a lot of damage if it got into your facility. They are easy to find and very cheap and you can find them on amazon for under $20.00

4. Boot knife

 A boot knife with a 3 inch or more blade length stainless steel is a very common item confiscated at checkpoints. I have seen many of these show up at a checkpoint and they typically have a blade length of 3 inches or more. Look for a case that is just plastic and does not have a metal clip (less metallic content and harder to detect).

Medium ITEMS: Knife or edged weapon threats plus IED components

This category is going to be the highest percentage of threat items your officers will encounter when they are conducting screening. If you run a public checkpoint you will collect hundreds of items in this category and they will typically be a knife.

I will talk about this in another post (Selecting the Best Walk Thru Metal Detector) but before you even test this category to buy a hand wand you need to verify that your walk thru will alarm to these items. Your walk through is what tells your officer they need to hand wand a person and if you walk thru will not detect (alarm) these items you are NEVER going to hand wand that person. So if your walk thru metal detector is not detecting the below test objects you are letting all of these items in you building. Oddly enough the NIJ standard never mentions this little bit of information.

1. Three inch pocket knife

A three inch pocket knife with metal case and a 3 inch pocket knife with a plastic case. When you test these you are going to see a huge difference between the metal cased knife and the plastic cased knife. The cheaper plastic cased knife has far less metallic content and is much harder to detect (walk thru metal detector). Almost all knives on the market today are stainless steel and they will provide you a good test for knives

 2. A two and one Inch blade plastic handle pocket knife with no metal clip.

If you not want knives in your building you need to check all the way down to a one inch blade knife. Look for the cheap all plastic handle knives as they will have the lowest metallic content. You can find them on amazon for very cheap and are perfect test objects for hand held and you walk through metal detector. Try to avoid the ones with clips as they have more metal.

Not all pocket knives are manufactured the same and this is another mistake with the NIJ test objects. You can buy 5 different pocket knives and they will have different amounts of metal used in their construction. The plastic case knives with no clip will get you the lowest metallic content to test and ensure you are testing for worst cases scenario. When I compared the NIJ test objects with off the shelf products I found them to be at the higher end of the different types of knifes. The means a knife that uses less metal will get past your walk thru metal detector if you set it to the NIJ Steel/stainless steel test object knives. Do not test the aluminum NIJ knife as this is for prisons (shank) as you cannot find a pocket knife on the market made out of just aluminum.

Not all pocket knives are manufactured the same and this is another mistake with the NIJ test objects. You can buy 5 different pocket knives and they will have different amounts of metal used in their construction. The plastic case knives with no clip will get you the lowest metallic content to test and ensure you are testing for worst cases scenario. When I compared the NIJ test objects with off the shelf products I found them to be at the higher end of the different types of knifes. The means a knife that uses less metal will get past your walk thru metal detector if you set it to the NIJ Steel/stainless steel test object knives. Do not test the aluminum NIJ knife as this is for prisons (shank) as you cannot find a pocket knife on the market made out of just aluminum.

3. Nine volt battery for IED’s

The nine volt is the first test object we are going to suggest to detect an IED. As a Bomb Technician I know an IED’s is very dangerous and very hard to detect when constructed with low metallic content. I have built fully constructed IED’s and walked them right through a metal detector set to the disassembled gun and NIJ knife settings. The 9 volt has historically been a very common battery used in IED construction so it is a good test object. When you are looking for an IED you are looking for the metal in the firing circuit and the power source is the one metallic item you can narrow down and measure. Not all 9 volts are the same so get a high quality one and also a cheap low quality and test both. You will find that the cheaper 9 volts have less metal and are a little harder to detect.

Small ITEMS: IED Components and very small threats

1. AA and AAA Batteries

These small batteries are also for testing against IED threats. Yes a blasting cap can be set off by an AA or AAA battery so you need to be able to detect a battery of this size. A typical military or commercial blasting cap only needs around .5 amperes to set it off and both an AA and AAA have the power to do this. I did testing with the ATF at FLETC and it was very eye opening as most people think you need a 9 volt or above to set off a cap (wrong). Test the high quality and low quality batteries as you will see a difference in how they respond.

https://www.academia.edu/17153788/Electrical_Blasting_Caps_Voltage_Requirements

2. Razor blades

Razor blades come in all different shapes and sizes so you need to test all of the different types to verify how the units will respond. Remember if you walk thru will not detect this you are not going to hand wand the person and this threat is coming into your building. I saw this happen when a women hid an exacto blade in her bra and when the judge sentenced her she started cutting herself. The Judge was very upset and wanted to know how this blade got in his courtroom and that is we got to remind him about how he would not let us raise the sensitivity of the walk through metal detector to detect this exact type of threat.

3. Cuff key

A Cuff is a must have test object if you are in a facility that handles prisoners. You DO NOT want this getting into your courtrooms and you need to make sure you can detect this type of threat. The honest to goodness truth is that your walk thru metal detector is not typically going to be able to detect this so you would again never hand wand (it is coming in). They do manufacture walk thrus with very high sensitivity (prison units) that can detect a cuff key so if you do not want this in your facility you need one of those units. The very common walk thrus that you see in most facilities cannot detect a cuff key. There are different types but the most common and hardest to detect is below:

 4. Metal Detector Correct Blasting Caps

A blasting cap is the 2nd item I am going to recommend for testing vs an IED threat. Blasting caps have very little metallic content and are very hard to detect in a walk thru metal detector. They come is 3 different types based on their metal content and sizes, Electrical copper and aluminum caps and non-electrical aluminum caps.

So you are not going to be able to get a real one so you need an “INERT Metal Detector Correct” blasting caps. We are just now finishing developing these so send me an e-mail and I can get you hooked up with the INERT caps. DO NOT use the training inert caps because they are NOT metal detector correct.

Step 2: Get the Hand Wands to Test:

Trying to get all these units to test is easy and you just need to contact the manufactures and tell them you want a unit to test. If they say no well move onto the next guy because when it comes to hand wands there are a ton of manufactures. The big companies like Garrett, CIEA, Ranger, etc. should provide you a unit no problem. You can also call around to your fellow Security Professionals and borrow one of their units to test. There are about 10 or more hand wands on the market so try and test as many as possible can so you get a very good sample size.

Step 3: Conduct the testing:

Make a checklist of all of your items and run your test for each hand wand. Have a person hid each item in the same spot and verify if the unit can detect and what the distance from the person’s body was when it detected. The reason you want to know this is because when you buy a hand wand the minimum distance that it detects all of your test objects in the distance you MUST tell your officers to hand wand a person (put this in your Post Orders). The key here is to repeat the test the exact same way each time and I recommended a minimum of 3-5 test per test object to verify you get the same response.

Most people do not know this but you need to test the hand wand against the test object at the following locations:

1. Back of the Paddle
2. Middle of the paddle
3. Top of the paddle

Hands wands will have varying levels of detection on the paddle and typically the top of the paddle you have to get closer to the object to detect. The can play a role in you scanning distance you put out to your Officers based on how the unit you selects performs. If you do not know this and your guys are scanning 2 inches away from the person, and the top will only detect at one inch you could miss a threat.

If you really want to see how the unit match up build an inexpensive test rig so you can measure the distance the threats alarm. All you need is about 3 foot of a 2X4 and wooden ruler and some rubber bands. The below is the test rig I used to do my testing and it worked great.

You will find that almost all of the units on the market can detect all of the test objects but some of them will have a hard time with the very small items (i.e. cuff key, razor blade). This is important if you are trying to mitigate an IED threat as some configuration of IED’s have very little metal and a hand wand must be sensitive to detect these components. I have tested most units and found that the less expensive models you have to get under 1 inch away from the very small threats to detect. While this is not bad you must ensure that if you purchase and deploy one of these units you have your officer’s scan at the lowest distance from the threats your test demonstrated.

Once you have completed the testing you can now factor in the different features on the units. As you get more features like vibration or a pin point capability the cost increases drastically. You will also find that the lower cost units are not built as rugged as the more expensive ones. You just need to make a decision based on your needs and the threat you are trying to detect. Once you know which ones can detect the best you can factor how much you are willing to spend for the detector? You may find that you do not need a $250.00 unit and a $50.00 unit will work just fine. Also do not get too wrapped up about a unit with pinpoint capability. I have tested many units and most can detect from the tip (Pinpoint).

You can shop around as there are a ton of companies that sell hand wands and you can get a good price by checking with each one. I have found that I can typically get them to come down if I show them the same unit from another company for less.

Conclusion:

The most important thing you need to remember is that there is a die hard relationship between your hand wand and walk through metal detector. They work together and the walk through is what tells your officers they need to hand wand a person. If you walk thru will not detect the items you do not want coming into the building you have a very serious problem that you need to get fixed. We can help you with you walk through settings and hand wand testing and even provide you training. Get into contact with us at the below and we can get you headed in the right direction and improve your ability to detect threats at your checkpoints.