DRYSTIK - Model ADS-2 - Active Moisture Exchanger With Duty Cycle Controller User Manual

DRYSTIK Model ADS-2 User’s Manual Active Moisture Exchanger with Duty Cycle Controller DURRIDGE Company Inc.524 Boston Road Billerica, MA 01821Tel: (978) 667-9556Fax: (978) 667-9557service@durridge.com www.durridge.comRevision 2012-08-31© 2012 DURRIDGE Company Inc.IntroductionThe DRYSTIK Model ADS-2 consists of a Nafion membrane tube with a purge sheath coiled in a box with a pump, flow-control needle valves, and a Duty Cycle Controller.Nafion, a material invented by DuPont and marketed by Perma Pure, consists of PTFE (Teflon) laced with hydrophyllic molecules that will pass water molecules from one to another down a humidity gradient in the material. If the humidity inside the membrane tube is higher than the humidity in the purge sheath then water molecules will be transported from inside the tube to the purge sheath. This is purely a chemical process. There are no micro-pores and other gases cannot cross the membrane.In the DRYSTIK Model ADS-2, the air inside the membrane tube is compressed, thus increasing the humidity and making the system much more efficient. The dessicant in a laboratory drying unit can be made to last for many months of continuous use, without replacement, instead of 10 days in typical conditions without a DRYSTIK.Compressing the incoming air causes water molecules to cross to the purge sheath even if the sheath is filled with fresh air at ambient humidity. Thus the system will start to dry incoming ambient air even without dry purging air in the sheath. If the dryer outlet air is circulated back to become purge air it will increase the efficiency of the drying process and the system becomes regenerative, bringing the air leaving the membrane tube to progressively lower humidity.A Duty Cycle Controller is built into the DRYSTIK to provide precise control of very low average sample flow rates. This is important for several applications including long-term soil gas monitoring.Ideally, the Nafion tube should be purged with dry air flowing at two or three times the sample flow velocity. However, with the incoming air compressed, the device is still effective even though only the dried sample air is used to purge the system. With 48” and 144” models, the relative humidity can be brought down below 10%, with no desiccant in the air path, but it is more efficient if desiccant is still used.Nafion is an amazing material. It loves water vapor. But its function is inhibited by the presence of liquid water. Compression of ambient air in high-humidity conditions can produce condensation in the membran tubing, that reduces the efficiency of the system. In those conditions, a cool trap between the pump and the membrane tube is recommended, and offered as an accessory. Reducing the duty cycle to around 20% also helps to mitigate the effect of condensation.2 © 2012 DURRIDGE Company Inc.Table of Contents1 GETTING STARTED 41.1 Unpacking 41.2 General Safety Instructions 41.3 DRYSTIK ADS-2 Packing List 4Fig. 1 Tubing set included with the DRYSTIK Model ADS-2 42 Using The DRYSTIK ADS-2 52.1 Connections and Controls 52.1.1 Front Panel 5Fig. 2 Front Panel 52.1.2 Back Panel 6Fig. 3 Back Panel 62.2 Monitoring Radon in Air 7Fig. 4 Basic setup for monitoring radon in air 7Fig. 5 Basic setup for monitoring thoron in air 82.3 Monitoring Thoron in Air 9Fig. 6 Alternative setup for monitoring thoron in air 92.4 High Humidity Conditions 10Fig. 7 DRYSTIK Configuration with Cool Trap 102.5 Monitoring Radon in Water 12Fig. 8 DRYSTIK Configuration wtih RAD AQUA 123 DRYSTIK Technology 133.1 Pump Airflow 13Fig. 9 DRYSTIK Pump Airflow 133.2 Nafion Tubing Airflow 13Fig. 10 DRYSTIK Pump Airflow 133.3 DRYSTIK Circuitry 14Fig. 11 DRYSTIK Circuitry 144 Performance Comparison 154.1 DRYSTIK Model 12ADS-2 15Fig. 12 DRYSTIK Model 12ADS-2 154.2 DRYSTIK Model 48ADS-2 16Fig. 13 DRYSTIK Model 48ADS-2 164.3 DRYSTIK Model 144ADS-2 17Fig. 14 DRYSTIK Model 144ADS-2 17© 2012 DURRIDGE Company Inc. 31 GETTING STARTED1.1 UnpackingFirst make sure your DRYSTIK ADS-2 package contains everything you are supposed to have. Examine the case contents and verify that you have all the items shown in the packing list. If anything is missing, please call DURRIDGE immediately at (978) 667-9556 or email sales@durridge.com.1.2 General Safety InstructionsThere is nothing hazardous to the user in the DRYSTIK Model ADS-2. To protect the DRYSTIK unit, do not let it come in direct contact with water. It is also important to prevent air samples containing liquid water from entering the unit’s Sample In port. This is covered in the usage instructions later in this manual.1.3 DRYSTIK ADS-2 Packing ListThe DRYSTIK Model ADS-2 system consists of the following components:• The main DRYSTIK console, with built-in Duty Cycle Controller• Tubing Set consisting of the following sections (See Fig. 1; tubing usage shown in Fig 4.)• A (x2): 36” long 1/8” ID• B (x1): 24” long 1/8” ID• C (x1): 3” long 5/15” ID to 36” long 3/16” ID to 3” long 1/8” ID• D (x1): 3” long 5/15” ID to 36” long 3/16” ID to 3” long 1/8” ID + Filter• 12V 1.24 Amp DC Power Adapter• Printed DRYSTIK ADS-2 User’s Manual Fig. 1 Tubing set included with the DRYSTIK Model ADS-21 GETTING STARTED© 2012, DURRIDGE Company Inc. 42 Using The DRYSTIK ADS-22.1 Connections and Controls2.1.1 Front PanelThe front panel of the DRYSTIK ADS-2 contains hose connections for the pump in and out, the membrane tube in with three outputs (low flow, high flow and needle valve), and the purge flow in and out. All the connections except the membrane tube outlets are always open.The membrane tube outlets are shut off except when a plug is inserted.The duty cycle controls consist of three buttons. Their function changes with respect to the current device status, and the current function of each button is indicated on the LCD above them. The operation is intended to be self-evident and intuitive. A detailed description is given later.Fig. 2 Front Panel2 Using the DRYSTIK ADS-2© 2012, DURRIDGE Company Inc. 52.1.2 Back PanelThe rear panel of the DRYSTIK ADS-2 contains a series of switches and ports. These are, from left to right, the Internal Pump / DCC Output toggle switch, the 12VDC Power Out port, the 12VDC Power In port, and the device ON/OFF switch. The Internal Pump / DCC Output toggle switch is used to specify whethe the DRYSTIK’s Duty Cycle Controller is used to cycle the internal pump, or an external device with power supplied by the DCC output port. The benefits of the duty cycle controller are thus available for a wide variety of other devices.Fig. 3 Back Panel2 Using the DRYSTIK ADS-26 © 2012, DURRIDGE Company Inc.2.2 Monitoring Radon in AirTo configure the DRYSTIK ADS-2 for monitoring radon in air, tubing from the sampling point is connected to the pump input. The pump output is connected to the Nafion tube input with a small tubing bridge that, preferably, includes the 5 micron filter supplied. The outlet may be taken from the low-flow outlet, which gives a nominal flow rate of 0.14 L/min. For fastest reduction, and lowest level, of humidity in the RAD7, a drying unit with new or regenerated desiccant may be placed between the Nafion tube outlet and the RAD7 inlet. The outlet of the RAD7 is fed to the purge inlet of the DRYSTIK to provide a counterflow purge of the sheath around the membrane tubing. The purge outlet may be left with nothing connected, or can be connected to downstream instruments. Fig. 4 Basic setup for monitoring radon in airBefore starting any measurement with the RAD7 it should first be purged for five minutes. This can be done by connecting the RAD7 to the high-flow output of the DRYSTIK and running it for five minutes with the RAD7 switched off, or by disconnecting the DRYSTIK and letting the RAD7 do its own purge (Test, Purge [ENTER]), to remove residual radon from any previous measurement. The RAD7’s purge can be stopped by pushing the menu button. The RAD7 should then be set to a preset protocol, 2 Using the DRYSTIK ADS-2© 2012, DURRIDGE Company Inc. 7such as 1-day (for 48 half-hour readings), or weeks (for indefinite monitoring, with two-hour cycles) and the pump turned off (Setup, Pump, Off [ENTER]). The DRYSTIK can be turned on, with the duty cycle set to 100% and the duty cycle controller 12V output sent to the pump (not the external socket, see switch at back of the DRYSTIK). The RAD7 measurement can be started at any time (Test, Start, [ENTER]). After an hour or so, the duty cycle of the DRYSTIK can be reduced to, say, 20%. This improves the efficiency and reduces wear and tear on the pump.The DURRIDGE PC software, CAPTURE, may always be used to download data from the RAD7. If no desiccant is used, particularly in hot and humid conditions, there may, even with the 144-ADS-2 model, still be a measurable correction to be applied for humidity in the RAD7. CAPTURE provides this correction to readings automatically provided the “correct for humidity” button is checked.Fig. 5 Basic setup for monitoring thoron in air2 Using the DRYSTIK ADS-28 © 2012, DURRIDGE Company Inc.2.3 Monitoring Thoron in AirThe significant difference between measuring radon and measuring thoron is the half life of thoron (56 seconds). Because this is so short, the delay between the air being sampled at the sampling point and being measured in the instrument is a cause of loss of sample by radioactive decay during sample acquisition. Thus it improves thoron sensitivity to minimize the volume of the sample acquisition path and use a high flow velocity. To that end, the “high flow” output is chosen and either no desiccant is put in the path to the RAD7 (Fig 5) or a small drying tube is put there (Fig 6).Fig. 6 Alternative setup for monitoring thoron in air1.The RAD7 pump should be turned off (Setup, Pump, Off [ENTER]) and the DRYSTIK duty cycle set to 100% (push the righthand button on the DRYSTIK front panel to adjust the duty cycle). Set the RAD7 protocol to ‘Thoron’ (Setup, Protocol, Thoron [ENTER]) then change the cycle length to your choice and turn off the RAD7 pump (Setup, Pump, Off [ENTER]). For long term monitoring we would recommend longer cycle times than the default 5 minutes; 15 or 30 minutes would be good. If a printer is in position, turn on the RAD7 and let it print out the header. Check the setup review to be sure all settings are what you expect.2 Using the DRYSTIK ADS-2© 2012, DURRIDGE Company Inc. 92.4 High Humidity ConditionsIf condensation occurs in the tube bridge, between the pump and the Nafion tube input, water will make contact with the Nafion. This should be avoided if possible. The most efficient way to deal with it is with a Cool Trap. DURRIDGE offers two sizes of Cool Trap, one that would fit in a mug and one that would fit in a bucket. The bucket size is more efficient, but has more volume . Either one can be placed in a container with ice water or other coolant, or mounted in the door (to avoid refrigerant tubes) of a refrigerator.The cool trap is intended to reduce the dew point of the compressed air down towards the temperature of the cool trap, preferably close to zero degrees celsius. Condensate is expelled through the drain. The drain needle valve should be adjusted so that a bubble appears occasionally. If the drain blows a bubble occasionally, we know that water is not accumulating in the reservoir. If the compressed air leaving the cool trap has a dew point below ambient temperature we can be confident that condensation will not occur inside the teflon membrane tube.Fig. 7 DRYSTIK Configuration with Cool Trap2 Using the DRYSTIK ADS-210 © 2012, DURRIDGE Company Inc.If no cool trap is available, slowing down the average flow rate reduces the rate of condensation and helps the nafion tube to deal with the condensed water. Use the low-flow output of the DRYSTIK and set the duty cycle to 20% or less. With the DRYSTIK switched ON, push the “Enter” button several times, until the option is to “change the duty cycle” that then goes to a screen showing the On time, the Off time and the duty cycle (DC). Pushing the + and - buttons will then increase or decrease the duty cycle. The lower the duty cycle, the lower the average flow rate, the easier the Nafion tube will deal with condensate and the less wear and tear on the pump. Please note, however, that very low flow rates may influence the performance of the RAD7. With a 10% duty cycle and a 0.14 L/min flow rate when the pump is ON, the average flow rate will be 0.014 L/min. The volume of the RAD7 and inlet tubing will be around 1L, so that without any desiccant it will take about 1/0.014 = 71 minutes for 1L of sample air to flow out of the DRYSTIK. That will require 1% to be added to the RAD7 reading to correct for the decay of the radon in the sample during sample acquisition. With a labortory drying unit in the sample acquisition path the correction should be nearly doubled. Please note, also, that the response time of the system with such a flow rate cannot be less than 70 minutes even if the RAD7 is put into SNIFF mode. For normal, long-term measurements, with the RAD7 in NORMAL mode after the first three hours, neither the 1% or 2% correction nor the one- or two-hour response time are of any concern.For continuous soil gas measurements, see below, the very low flow rate is a distinct advantage.2 Using the DRYSTIK ADS-2© 2012, DURRIDGE Company Inc. 112.5 Monitoring Radon in WaterIf there is any chance of water entering the DRYSTIK, precautions must be taken to prevent it. The airtight water switch is a good solution. This should be inserted in the air sample path upstream of the DRYSTIK. The water switch is connected to the 12V supply and the 12V output of the water switch is connected to the DRYSTIK 12V power inlet. When water enters the water switch, it raises a float that interrupts the 12V supply, thus stopping the pump in the DRYSTIK.Fig. 8 DRYSTIK Configuration wtih RAD AQUA2 Using the DRYSTIK ADS-212 © 2012, DURRIDGE Company Inc.3 DRYSTIK Technology3.1 Pump AirflowThe DRYSTIK’s Sample In and Pump Out ports are bridged internally with tubing connecting to a filter and pump, as shown in Fig. 9.Fig. 9 DRYSTIK Pump Airflow3.2 Nafion Tubing AirflowFigure 10 illustrates the DRYSTIK’s second air path, which contains Nafion tubing and a set of ports used to seperate moisuture out of the air sample. Once the sample has been dried, it exits the system through one of three outputs: a High Airflow port, a Low Airflow port, and an adjustable Needle Value port. Fig. 10 DRYSTIK Pump Airflow3 DRYSTIK Technology© 2012, DURRIDGE Company Inc. 133.3 DRYSTIK CircuitryFigure 11 illustrates the basic connections between the switches and ports on the rear panel of the DRYSTIK. When turned on, the Power Switch enables all system functions. The Pump/Output toggle switch controls whether the Duty Cycle Output feeds power to the internal pump or to the DCC output port. The second option makes it possible to use the Duty Cycle Controller to control a different instrument, such as an external pump.Fig. 11 DRYSTIK Circuitry3 DRYSTIK Technology14 © 2012, DURRIDGE Company Inc.4 Performance ComparisonThe following results were obtained in typical laboratory conditions of about 22? and around 50% relative humidity.4.1 DRYSTIK Model 12ADS-2Under typical operating conditions, the basic 12-inch DRYSTIK ADS-2 is able to separate moisture out of an air sample to approximately 6% relative humidity. This can be achieved in under fifteen minutes. This assumes a 100% duty cycle for the DRYSTIK’s internal pump, and the use of the Low Flow Rate output port.Fig. 12 DRYSTIK Model 12ADS-24 Performance Comparison© 2012, DURRIDGE Company Inc. 154.2 DRYSTIK Model 48ADS-2Under the same operating conditions described in Section 4.1, above, the 48-inch DRYSTIK ADS-2 is able to reduce the humidity of an air sample to approximately 4% relative humidity. This compares favorably with the 6% relative humidity achieved by the 12-inch DRYSTIK. With the 48-inch DRYSTIK, the humidity level stabilizes after about 30 minutes.Fig. 13 DRYSTIK Model 48ADS-24 Performance Comparison16 © 2012, DURRIDGE Company Inc.4.3 DRYSTIK Model 144ADS-2The top performing DRYSTIK is the 144-inch model, which achieves relative humidity levels of under 2% under the same conditions outlined in the previous scenarios. As with the 48-inch DRYSTIK, the 144-inch model produces stable humidity values after about 30 minutes.Fig. 14 DRYSTIK Model 144ADS-24 Performance Comparison© 2012, DURRIDGE Company Inc. 17