Vapor Pin

Vapor Pin

The Vapor Pin is a sampling device that has a variety of applications, including but not limited to  sub-slab soilgas sampling:

  • de-pressurization studies/ testing.
  • stray gas evaluations, source area characterization.
  • pilot testing and mitigation progress monitoring.

The Vapor Pin® specifically was designed to eliminate many of the problems associated with traditional sub-slab soil-gas sampling methods.

Description

The Vapor Pin®is a sampling device that has a variety of applications, including but not limited to  sub-slab soilgas sampling:

  • de-pressurization studies/ testing.
  • stray gas evaluations, source area characterization.
  • pilot testing and mitigation progress monitoring.

The Vapor Pin® specifically was designed to eliminate many of the problems associated with traditional sub-slab soil-gas sampling methods.
The patented design of the Vapor Pin® provides environmental professionals a means of collecting high-quality, low-cost soil-gas samples and pressure readings within minutes.

Applications

Using Vapor Pins® sampling device for Vapor-Intrusion Assessments
The Vapor Pin® sampling device has a number of applications, but it was designed to collect soil gas for vapor-intrusion assessments, and it does it well. The soil gas directly beneath a building floor, “subslab” soil gas, best represents the risk of vapor-intrusion, because it is the next closest thing to indoor air. But unlike indoor air, subslab soil gas generally does not contain background contamination from indoor or outdoor sources. Subslab soil gas more representative of indoor conditions than deep soil gas, and it’s easier to collect using hand-held equipment.

Subslab soil gas is normally collected prior to sampling indoor air. One or more Vapor Pin® sampling devices are installed by drilling 5/8-inch holes through the floor with a hammer drill, and installing them, as described in the Standard Operating Procedure (SOP). For a one-time sampling event, one can use brass Vapor Pins® installed in the stick-up configuration. If repeat sampling is needed, we recommend installing stainless-steel Vapor Pin® sampling device in the flush-mount configuration.

After installing the Vapor Pin® sampling device and allowing soil gas to equilibrate for two hours or more, connect the Summa canister, TO-17, or other sample container to the Vapor Pin® sampling device, purge the dead space in the sample train, and collect the sample, as described in the SOP. As discussed in the memorandum “Using Vapor Pins® sampling device for Source Characterization”, vapor sources are often located away from obvious locations, such as buried tanks and degreasing areas, so we recommend conducting field screening at additional locations when working near potential source areas.

Always follow the appropriate guidance when assessing vapor intrusion. Some regulatory agencies allow or encourage the use of the Vapor Pin® sampling device, but some guidance might preclude the use of some devices.

Using Vapor Pins® sampling device for Source Characterization
The Vapor Pin® sampling device is ideally suited for locating Volatile Organic Compound (VOC) contamination sources beneath the pavement. Our experience is that most sites have sources of contamination that in addition to those associated with underground tanks and degreasing areas. Unsuspected source areas often correspond to former exterior doors that were obscured by later building expansion. Cox-Colvin has located such sources equipped with little more than some Vapor Pin® sampling devices, a hammer drill, and a multi-gas meter.

Cox-Colvin’s approach to VOC source investigation consists of installing Vapor Pin® sampling devices along a grid, allowing the points to equilibrate, and collecting readings with a multi-gas meter. With a team of two people, we’ve installed as many as 90 Vapor Pin® sampling devices in one day and sampled, removed the Vapor Pin® sampling devices, and plugged the holes on the following day.

For source characterization, we normally install brass Vapor Pin® sampling devices in the stick-up configuration on a grid spacing of 20 to 30 feet. We cover the Vapor Pin® sampling devices with traffic cones and allow them to equilibrate for at least an hour. We then collect field readings with a hand-held multi-gas meter capable of measuring VOCs via Photo-Ionization Detector (PID), oxygen (O2), and Lower Explosive Limits (LEL). The PID indicates VOC sources. O2 in soil gas is normally lower than in air, but unusually low levels (<5%), especially with high LEL readings, are characteristic of methane generation (methanogenesis).
Methanogenesis occurs when non-chlorinated solvents or other organic matter degrades at too high a rate for O2 replenishment.

After collecting field readings at all of the sample points, samples are collected from locations with elevated PID readings, and submitted to a laboratory for confirmation. Samples can be collected into evacuated glass vials, Bottle Vacs, Tedlar bags, Summa canisters, sorbent tubes, and potentially other devices. Some containers do not offer low enough reporting levels for vapor intrusion sampling, but low levels are probably not needed for locating contaminant sources. At the conclusion of sampling, remove the Vapor Pin® sampling devices and fill the holes with hydraulic cement or caulk.

Urethane and polyurethane caulks are recommended by radon mitigation guidance for filling holes and cracks, but they contain VOCs that could interfere with subsequent sampling. Hydraulic cement does not contain VOCs, but it sets up quickly, making it potentially difficult to fill borings to total depth.  After removing the silicone sleeve and other plastic parts from the Vapor Pin® sampling devices, decontaminated them for reuse. Cox-Colvin has a number of Vapor Pin® sampling devices that they have used an average of seven or eight times with no breakage or damage.

 

Using Vapor Pin® sampling devices for Pressure Field Extension Testing
Vapor Pin® sampling devices are widely used for Pressure Field Extension (PFE) tests of radon and vapor-mitigation systems. The PFE test (also called a “Suction Field Extension Test” or “Communication Test”) ensures that a sub-slab depressurization (SSD) system creates sufficient vacuum everywhere beneath a floor. PFE testing is essential for proper system design and installation, and periodic testing in subsequent years verifies that the SSD continues to operate within specified limits. A common approach to measuring subslab vacuum is to drill a hole in the slab, jam a manometer into the hole, and take a reading, while running a radon fan or shop vacuum at the suction pit. Unfortunately, it can be difficult to form a tight seal between the manometer and the slab, and the test hole cannot be left open for subsequent testing.

A better approach for PFE testing is to measure the sub-slab vacuum through a Vapor Pin® sampling device. The Vapor Pin® sampling device provides a tight seal against the slab, and with the Vapor Pin® Cap in place, prevents the loss of soil gas to indoor air. The Vapor Pin® sampling device can be left in place indefinitely for subsequent measurements, or removed and reused elsewhere. For radon testing, the Vapor Pin® sampling device can be reused by simply cutting off and replacing the silicone sleeve between holes. For vapor-intrusion use, the Vapor Pin® should also be decontaminated before moving it to a different location.

For conducting PFE tests during pilot testing, the Vapor Pin® sampling device can be installed in the stick-up configuration, which requires drilling a 5/8-inch diameter hole in the slab. If the Vapor Pin® will be left in place for subsequent testing, it is typically installed in the flush-mount configuration, so that it doesn’t pose a trip hazard. The flush-mount installation requires drilling a 1-1/2 diameter inch hole and a 5/8-inch diameter hole. The flush-mount Vapor Pin® sampling device may be covered with Cox-Colvin’s stainless steel Secured Cover, which reduces the risk of tampering, or a black plastic Flush Mount Cover, which is more economical. We recommend using brass Vapor Pin® sampling devices for one-time use, such as pilot testing, and stainless steel Vapor Pin® sampling devices if points will be left in place for subsequent testing.

Title

  • Reduces damage to the slab
  • Improves diagnostic testing
  • Improves spatial resolution
  • Connects easily to sampling equipment
  • Is easily installed, sampled, and retrieved for reuse
  • Eliminates the need for grout, increasing productivity
  • Reduces sampling time, allowing collection of more samples for less cost, and improves the understanding of
    site conditions
  • Unique patented design reduces the potential for leaks and improves sample quality

Extraction

Extracción

Instalación y herramientas

Installing and tools

Installation of the secure covers

Live Demo con Leak test

Introduction to the us of Vapor Pin

Introducción

Why does my Vapor Pin® sampling device fail a helium leak test?

We can’t rule out leakage, but it’s rare with Vapor Pin® sampling device, and if you detect helium at multiple sample points, it might be caused by false positives from methane. Most helium detectors respond positively to methane. Similarly, high concentrations of C5-C12 hydrocarbons in soil gas have been reported to cause false positives in helium detectors. Methane generation is common when oxygen is depleted by high concentrations or large sources of hydrocarbons, especially in petroleum products containing ethanol. This is one of the reasons that Cox-Colvin encourages leak testing via mechanical means, as described in our SOP Leak Testing the Vapor Pin® sampling device via Mechanical Means (located under our Resources Page), and as discussed in the Interstate Technology & Regulatory Council (ITRC), 2014 Petroleum Vapor Intrusion guidance. If you do use a helium leak detector, we recommend using a model that does not respond to methane, and test the soil gas for false positives before applying helium.

 

What are the Metric Measurements for installing the Vapor Pin sampling device;?

Use 16mm for the pin and 38mm for the covers, we suggest 400mm cutting length for both sizes.

 

Does the Vapor Pin® sampling device connect to Swagelok fittings?

The FLX-VP was specifically designed to connect to a variety of other devices including Swagelok compression fittings. The standard Swagelok connection for 1/4” OD Nylaflow and Teflon tubing, and for TO-17 sorbent tubes is available through the Vapor Pin® sampling device website (Part Number SL_FLX1_Fitting). Replacement ferrule sets are also available.

 

Soil Gas Siloxane Contamination

First and foremost, there may be specifics required by regulators in your state…by in general…

Silicone tubing is more reactive than harder tubing, which is to say that Silicone, and softer tubing generally, is more prone to absorbing and outgassing organic compounds.  Greg Ouellette’s 2004 Soil Vapor Sampling and Analysis – Lessons Learned, DOE/PERF Soil Vapor Workshop, Brea, CA Jan. 27-29, is one of several reports that demonstrates the higher reactivity of soft tubing, this is out of context for our application.  Ouellette drew vapors through 50 ft of Tygon tubing, which has approximately 85 square inches in contact with soil gas.  In the case of the Vapor Pin®, the only contact between soft tubing (Silicone) and soil gas is the cross sectional area between the slab and the bottom of the pin, which is 0.11 square inches.  I think we also agree that while Silicone would absorb some VOCs, the tubing would reach equilibrium at some point and stop absorbing vapors.

We test the Silicone tubing when it arrives by drawing ambient air through the entire 50 ft lengths with a PID, and record the readings.  The tubing does contain a few ppm of vapors in the first few days, specifically siloxanes, which are not on any vapor intrusion list.  We continue to test for several days until the entire length of tubing contributes less than 1 ppm of VOCs.  We then cut the tubing into short lengths and let them continue to air before sending them.

They are relatively obscure issues such as what kind of helium to use during leak testing, or whether to use barbed versus compression fittings, when most of the problems boil down to a few issues:

1)      Run a shut-in leak test on the assembled canister & regulator, as described in  ASTM D7663-11, before going to the field.  Leak test the assembled sample train on site, except for the connection to the Vapor Pin® sampling device or equivalent point with a hand-held vacuum pump or peristaltic.  Last, connect the sample train to the sub-slab point and leak test it the point.  Helium works, but we use distilled water.  That’s a problem if the point leaks, but I’ve never seen it with the Vapor Pin® sampling device.  We also check the regulator flow rate prior the shut-in test, but an improper flow rate is more likely to result in no sample than an invalid sample.  We’ve developed our own techniques if you’re interested.  Also, documenting your test results and presenting them to the lab improves your credibility and keeps them on their toes.  Even the best labs occasionally provide faulty equipment.

2)      Minimize the lengths of soft tubing by butting up the harder tubing or hardware against each other as close as possible.  We find compression fittings more likely to leak, not less.

3)      Avoid incompetent labs if you have a choice.

4)      Collect an adequate number of samples to evaluate spatial heterogeneity.  This may be the most important part.  At least when working near sources, we’ve repeatedly found that the primary source isn’t where we expected it to be, and our best guess would have provided concentrations that are orders of magnitude lower than maximum.  The only solution is to drill lots of holes, which is practical with the Vapor Pin®.  I’ve personally installed as many as 56 in a day, and my younger coworkers have hit 90.  In many cases you can screen them with a PID and collect a select few for lab analysis.

Please refer to our White Papers under resources for additional information.  One with the Michigan DEQ in which we installed four Vapor Pin® sampling device next to their “conventional” sub-slab points (Swagelok fittings set in cement).  They used a variety of labs, sample containers, and analytical methods over the course of months.  But any way we cut it, when we plot the Vapor Pin® against conventional points, we get a good correlation.  The second white paper was done in conjunction with H&P labs in San Diego.  Their sub-slab points, as described in the CA guidance, amount to miniature monitor wells, complete with sand packs and screens.  They collected 10 sample pairs, and again, the correlation is excellent.  In spite of all the issues concerning the Silicone sleeves, the Tygon used to make connections, and others issues we haven’t touched on, the fact that we get the same results over a broad range of concentrations and compounds proves that the Vapor Pin® sampling devices does what it’s designed to do.

 

How is the Vapor Pin® sampling device better than existing methods for sub-slab vapor sampling?

The Vapor Pin® sampling device is superior to other sub-slab vapor sampling methods because: 1) it’s constructed of a single piece of metal, eliminating potential leak points; 2) it’s installed in minutes using common hand tools; 3) it uses a silicone sleeve to form an air-tight seal between the Vapor Pin® sampling device and the side of the borehole, eliminating the need for grout or other adhesives; and 4) unlike other sampling devices, it’s easily retrieved for reuse.

The Vapor Pin® sampling device is superior to other sub-slab vapor sampling methods because: 1) it’s constructed of a single piece of metal, eliminating potential leak points; 2) it’s installed in minutes using common hand tools; 3) it uses a silicone sleeve to form an air-tight seal between the Vapor Pin® and the side of the borehole, eliminating the need for grout or other adhesives; and 4) unlike other sampling devices, it’s easily retrieved for reuse.

 

Can the Vapor Pin® sampling device be used to sample all VOCs?

The Vapor Pin® sampling device provides a means of transmitting soil gas through the slab so that it can be sampled. The particular suite of VOCs that will be reported is dependent on the analytical method employed by your laboratory.

Can the Vapor Pin® sampling device be installed as a flush mount?

Yes, the Vapor Pin® sampling device is designed to be installed in the stick-up or flush mount configuration. We recommend the Vapor Pin® sampling device be installed in the stick-up configuration if it will be used for a single sampling event and then removed, and in the flush-mount configuration if it will be left in place for repeated sampling. Plastic flush-mount covers are supplied with the Vapor Pin® Kit, but stainless steel Secure Covers are also available and provide more protection from damage or tampering. The Standard Operating Procedure (SOP) Use of the Vapor Pin® Drilling Guide and Secure Cover describes the flush-mount installation procedure. As described in the SOP, the optional Drilling Guide simplifies flush-mount installation and increases the accuracy of hole depth and location.

 

Can the Vapor Pin® sampling device be used for vapor intrusion sampling?

The Vapor Pin® sampling device was designed for use in vapor intrusion studies as well as source delineation. We suggest that your applicable guidance be consulted to obtain appropriate leak detection procedures, soil gas flow rates, appropriate sample containers, and appropriate length of the sampling period. The Vapor Pin® sampling device should be left in place if multiple rounds of sampling are required. Many states specifically allow the use of the Vapor Pin® for vapor intrusion sampling, but we recommend you consult the guidance for your state or jurisdiction to be sure.

Exactly what’s included in the Vapor Pin® Kit?

Vapor Pin® kits are available in four variations. The standard Vapor Pin® Kit consists of the following items, all conveniently contained in a Hard-Sided Carrying Case: 10 Vapor Pins® (brass or stainless steel); 20 Silicone Sleeves, 20 Vapor Pin® Caps, 10 plastic Flush Mount Covers; 1 Installation/Extraction Tool; 1 Brush; 1 Water Dam for leak testing; and 1 Vapor Pin® Standard Operating Procedure.

The Contractor Kit contains the same equipment as the Standard Kit, plus 1 Stainless Steel Drilling Guide, 10 Secure Flush Mount Covers (in place of 10 plastic covers), and 1 Spanner Screwdriver for installing and removing the secure covers. The Contractor Kit offers more protection from damage or tampering than the Standard Kit, but either can be used for flush mount or stick-up installations.

We recommend that you initially purchase a Vapor Pin® Kit to ensure all required components are obtained. Afterward, individual components of the Kit can be purchased as needed. Sample tubing also is available separately. Also available separately is the Elastrator tool, which simplifies the process of placing the silicone sleeve onto the Vapor Pin® prior to installation.

 

Is there an easier way to install the silicone sleeve on the Vapor Pin® sampling device?

We recommend you screw the Vapor Pin® sampling device into the installation tool, and push the sleeve over the lower end of the Vapor Pin® sampling device. The optional Elastrator tool eases this process, by placing the Elastrator tips into the end of the silicone sleeve and squeezing the tool’s handle to open the sleeve as you push it onto the Vapor Pin® sampling device. We polish Vapor Pins® prior to shipment to reduce sharp edges, but you should still wear work gloves while installing the sleeve.

How long does it take to install a Vapor Pin® sampling device?

The Vapor Pin® sampling device can be installed in the stick-up configuration in less than five minutes. Installation in the flush-mount configuration requires an additional two or three minutes.

What do I need to install a Vapor Pin® sampling device?

The Vapor Pin® sampling device is installed easily using common hand tools. We recommend purchase of the Vapor Pin® Kit, which includes just about everything required for 10 Vapor Pin™ installations. The only tools needed (in addition to the Vapor Pin® Kit) are a hammer drill and appropriate bits, and a dead blow hammer. See the Vapor Pin® Standard Operating Procedure for details. Grout or other adhesives are NOT required.

What kind of drill and bits does Cox-Colvin use during Vapor Pin® sampling device installation?

We use a hammer drill manufactured by Hilti (TE 50 Deluxe Grounded Combihammer, item # 383916), with hammer drill bits TE-YX 5/8 inch x 22 inch (item # 206514) and TE-YX 1-1/2 inch x 23 inch (item # 293032). Available by calling +34 872 080 542. Comparable drills and bits are available from other manufacturers as well.

For metric measurements – Use 16mm for the pin and 38mm for the covers., we suggest 400mm cutting length for both sizes.

How long after installation before I can sample a Vapor Pin® sampling device?

Because the Vapor Pin® sampling device does not require the use of grout, it can be sampled as soon as the sub-slab soil gas has reached equilibration. The period of time may be prescribed by your particular guidance, but can be as little as 20 minutes following installation, since Vapor Pin™ installations result in very short hole-open times.

What kind of tubing do I need for soil-gas sampling?

Theoretically, stainless steel is best because it has the lowest reactivity (e.g., it’s less likely to absorb or give off vapors), but flexible plastic tubing is the norm because it’s easier to handle, more affordable, and entirely satisfactory if proper precautions are followed. In general, softer tubing is the more reactive than harder tubing. Semi-rigid Nylon and Teflon tubing are most widely recommended for soil-gas sampling, but others might be acceptable, depending on the applicable guidance.

Most or all Summa-type canisters, and many other sample containers and fittings, are designed to accept 1/4-inch outer diameter (OD) tubing. Cox-Colvin offers 1/4-inch OD, Nylaflow LM, which has superior chemical resistance to generic nylon tubing and is less costly than Teflon. Poly tubing’s chemical reactivity makes it inappropriate for vapor-intrusion sampling, but it might be suitable for high-concentration vapors near source areas. All plastic tubing should be replaced between samples, and stored and handled away from vapor sources. Soft tubing, such as Tygon™, is recommended only for making connections between semi-rigid tubing and other devices, as discussed below.

 

How do I connect sample tubing to the Vapor Pin® sampling device and other equipment?

Most Summa-type canisters and regulators are equipped with Swagelok™ compression fittings which connect to 1/4-inch outer diameter (OD) tubing, including Nylaflow, with Swagelok™ ferrules and a hexagonal nut. The nut can be reused, but the ferrules are not, except on stainless steel tubing. Many laboratories will provide Swagelok™ ferrules that fit their sample canisters at a nominal cost.

 

How much soil gas should be evacuated from the Vapor Pin® sampling device prior to sampling?

The applicable guidance document might specify a particular number of purge volumes, but two or three volumes are commonly recommended. For the Vapor Pin® sampling device, one purge volume is equal to: 0.83 milliliters (ml) for the Vapor Pin™, plus 5.0 ml for each inch of hole beneath the Vapor Pin® sampling device, plus 0.42 ml for each inch of tubing, if using 1/4-inch OD Nylaflow LM, plus the internal volume of any other fittings or hardware in the sample train.

If you wish to calculate purge volume on the basis of equipment dimensions, the Vapor Pin® has a total length of 3.25 inches, of which 2 inches are inside the 5/8-inch hole in the slab, and 1.25 inches are above the 5/8-inch hole. The inner diameter (ID) of the Vapor Pin® sampling device is 0.187 inches. The Nylaflow LM tubing has an outer diameter (OD) of 0.25 inches and an ID of 0.187 inches. The Tygon™ tubing has an OD of 0.312 inches and an ID of 0.187 inches. Bear in mind that the Tygon™ tubing will expand in use, and because it should be used in short lengths to minimize contact with soil gas, its ID will typically not be part of the purge-volume calculation.

Cox-Colvin prefers to purge soil gas with a combination photo-ionization detector (PID) and oxygen (O2) meter and collects the sample after the PID and O2 levels stabilize, which indicates the presence of soil gas. VOCs and O2 typically stabilize after purging 50 ml to 100 ml of soil gas, which, depending on slab thickness and tubing length, generally equals around three purge volumes.

 

Will the silicone tubing surrounding the Vapor Pin® sampling device affect my sample?

We use peroxide-cured silicone tubing with the Vapor Pin® sampling device. Our studies indicate that the tubing does not affect the sample results. The tubing surrounds the bottom half of the pin forming the seal between the 5/8-inch hole and the Vapor Pin® sampling device. Sub-slab vapors are exposed to very little of the silicone tubing. Side-by-side comparisons with conventional sample points indicate that no vapors are added to or subtracted from soil gas by the silicone sleeve. Additionally, Cox-Colvin screens the silicone tubing upon arrival to ensure that sleeves with elevated levels of VOCs are not sent to customers.

Can a Vapor Pin® sampling device be re-used after extraction?

Yes – the Vapor Pin® sampling device is designed to be re-used after removal from the slab. Cox-Colvin has used some Vapor Pin® sampling devices at least a dozen times, with no obvious signs of wear. The sleeve and the protective cap should be replaced between locations, and the Vapor Pin® sampling device should be properly decontaminated in accordance with the Standard Operating Procedure.

How do I decontaminate the Vapor Pin® sampling device between installations?

Vapor Pin® sampling device decontamination is described in the Standard Operating Procedure, and consists of removing and discarding the silicone sleeve and protective cap, cleaning the Vapor Pin® sampling device in an Alconox or equivalent solution, rinsing thoroughly, and heating it to a temperature of 130°C.

Can I leave a Vapor Pin® sampling device in place between sampling events?

Yes. The Vapor Pin® sampling device can stay in place as long as necessary. For repeated use, we recommend a flush mount installation using a stainless steel Vapor Pin® sampling device to protect the pin from damage and corrosion. Keep in mind that the flush mount cap is not watertight and should not remain in place in areas subject to contaminant spills. If future sampling is not required, the Vapor Pin® sampling device should be removed and the hole in the slab filled with hydraulic cement.

Will the Vapor Pin® sampling device leak vapors into the building if I leave it in place?

If properly installed with its protective cap, there will be no vapor leakage into the structure through the Vapor Pin® sampling device. Our experience, and that of our customers, is that the Vapor Pin® sampling device is less likely to leak than other devices. 

Will the Vapor Pin® sampling device cause damage to the floor?

Installation of the Vapor Pin® sampling device will result in a 1.5-inch diameter hole (flush mount installation), or a 5/8-inch hole (stick-up installation). After the Vapor Pin® sampling device is removed, the hole should be patched with hydraulic cement. Beyond this, there should be no damage to the floor, and the Vapor Pin® causes no more damage than other methods of sub-slab sampling. 

Can the Vapor Pin® sampling device be used in slabs of any thickness?

The Vapor Pin® sampling device was designed to be used in slabs that are at least three inches thick. If the Vapor Pin® sampling device will be installed as a flush mount, we suggest that the slab be at least four inches thick. Because the Vapor Pin® sampling device does not have to extend to the bottom of the slab, there is no maximum slab thickness, provided your drill bit is long enough to drill into sub-slab. A 5/8-inch drill bit with a length of 24 inches covers most situations.

Does anyone else make something like the Vapor Pin® sampling device?

We’re not aware of another device quite like the patented Vapor Pin® sampling device. Other types of sub-slab sampling devices installed with cement are available, and some practitioners construct their own from plumbing parts. But the cost of locating parts, problems with leakage, and the fact that once installed, they normally can’t be reused, makes them more costly in the long run. We believe the Vapor Pin® sampling device will become the new standard for sub-slab vapor sampling because it’s easy and quick to install and use, it can be used over and over, and it provides quality samples with little or no leakage.

Should I purchase brass or stainless steel Vapor Pin® sampling devices?

Cox-Colvin typically uses brass Vapor Pin® sampling devices for temporary installations (one-time sampling) and stainless steel for long-term installations (repeated sampling), due to the superior corrosion resistance of stainless steel. If there is any doubt, we recommend purchasing stainless-steel pins, as the additional cost is a small part of overall costs, particularly after the Vapor Pin® sampling device has been used multiple times.

Is there a way to attach a piece of tubing, a filter, or other accessories to the bottom of the Vapor Pin® sampling device?

Vapor Pin® sampling devices are manufactured with a female thread at the bottom specifically for attaching a Barbed Adapter, available at the Cox-Colvin website. The Barbed Adapter allows you to attach tubing to the bottom of the Vapor Pin® sampling device to increase sample depth, to add a particulate filter such as an aquarium bubbler, etc. The Barbed Adapter has the same size barb as on the top of the Vapor Pin® sampling device and fits the same tubing.

You can also increase the sample depth with Cox-Colvin’s Vapor Pin® Extension, which also screws into the bottom of the Vapor Pin™. The Extension has male threads at the top and female threads at the bottom, allowing you to screw them together to extend the sample depth as much as desired in 1.5 inch increments.

Because the Vapor Pin was designed to be rugged and compatible with other sampling hardware, it has a nominal 1/4-inch barbed fitting at the top. Like other barbed fittings, it is actually somewhat larger than 1/4 inch in diameter, so the Vapor Pin™ is joined to semi-rigid tubing, e.g. Nylaflow, with a short piece of soft tubing. Cox-Colvin offers Tygon™ R-3063 tubing to make these connections. Tygon™ offers better chemical resistance than other soft tubing, but is pliable enough to make a tight seal. The Tygon™ tubing is placed between the Vapor Pin® sampling device and the semi-rigid tubing and fits over both of them. Pressure gauges, tee fittings, and other devices with a 1/4-inch barb can be attached to the sample train with Tygon™ tubing. The sample train can also be assembled with compression fittings if desired, but the additional ferrules required at each connection adds to sampling time and costs. Also, in our experience, barbed fittings are less likely to leak than compression fittings, especially under negative pressure. In fact, Missouri’s 2004 vapor-intrusion guidance discourages compression fittings at all points except at the sample canister, due to their tendency to leak.

Tygon™ has better chemical resistance than softer tubing, such as silicone, but silicone’s high flexibility allows connecting devices of different diameters. Silicone can also be penetrated with a hypodermic syringe for some types of sampling, after which the tubing automatically seals the hole. As with all environmental sampling, make sure your equipment complies with regulatory requirements and Data Quality Objectives.

Please notice that chemical interference from tubing is dependent upon many factors, but tubing is more likely to contribute hydrocarbons than chlorinated compounds. To minimize the risk of chemical interference from all tubing, reduce tubing lengths as far as possible, particularly soft tubing, and keep tubing away from vapor sources during storage and transport.

Does the Vapor Pin® sampling device provide a tight seal against the slab?

Under normal circumstances with proper installation through a concrete slab, the Vapor Pin® sampling device provides an air-tight seal. Cox-Colvin has leak tested the Vapor Pin® sampling device with helium; with 99% helium in the leak-test shroud, no helium (<50 ppm) was detected in soil gas. In some situations, such as a thin concrete slab or cracked and degraded concrete, or a hole greater than 5/8-inch diameter, may result in a poor seal. We recommend leak testing as part of the sampling procedure.

How should I leak test the Vapor Pin® sampling device?

As with all vapor-intrusion sampling, you’re encouraged to follow applicable guidance requirements. Cox-Colvin prefers to leak test the sub-slab sample point (Vapor Pin®) with distilled water, and the remaining sample train (canister, tubing, and fittings) via vacuum, as described in the Standard Operating Procedure Leak Testing the Vapor Pin® sampling device via Mechanical Means. Of course, the Vapor Pin® sampling device can also be leak tested with helium or other tracer gases, the same as with other sub-slab sample points.  If the method of leak testing is not specified, an alternative can be the water dam.

SOP- Homemade Play Dough for Leak Testing the Vapor Pin® with the Water Dam

VP Leak Testing with Water Dam SOP

Conduct leak tests in accordance with applicable guidance. If the method of leak testing is not specified, an alternative can be the water dam and vacuum pump, as described in SOP Leak Testing the VAPOR PIN® via Mechanical Means. For flush-mount installations, distilled water can be poured directly into the 1 1/2 inch (38mm) hole.

The Standard Kits come in 3 varieties* and Include:
• 10 VAPOR PINS®
• 20 VAPOR PIN® Sleeves
• 20 VAPOR PIN® Caps
• 10 Plastic Flush Mount Covers
• 1 Installation/Extraction Tool
• 1 Bottle Brush
• 1 Water Dam for leak testing
• Vapor Pin® SOPs
• Hard-sided carrying Case

The Contractor Kits come in 4 varieties*
and Include:
• 10 VAPOR PINS®
• 20 VAPOR PIN® Sleeves
• 20 VAPOR PIN® Caps
• 10 Stainless Steel Secure Covers
• 1 Spanner Screwdriver
• 1 Stainless Steel Drilling Guide
• 1 Installation/Extraction Tool
• 1 Bottle Brush
• 1 Water Dam for leak testing
• Vapor Pin® SOPs
• Hard-sided carrying Case

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