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SASS 2300 /SASS 2400 Wetted-Wall Air Samplers
Frequently Asked Questions
How does SASS 2300 control and adjust the airflow rate caliber that is input into the device?
The fan is operated at a constant RPM, so the airflow is constant, independent of battery or mains voltage. Of course, if you took it onto a high mountain where the air density was much different, there might be a small change in the actual flow rate.
It is calibrated with an orifice-style flowmeter at the factory before shipment. If you compare it with some other type of flowmeter, you have to be careful that the flowmeters airflow resistance does not affect the reading, that is, slow the flow of air down. Our calibration flowmeters have a pressure drop of only about 0.25 cm of water at 300 liters/minute. The overall pressure difference driving air through the SASS 2300 is only about 5 to 6 cm of water. That is why it can operate on a battery for such a long time. It has been designed to very efficiently use the air capability of the fan.
Can PBS be used instead of distilled water? Will it have problems with the salt content?
You cannot replace the make-up water in the make-up reservoir with PBS, since it will result in increasing sample salinity with long operating time. We maintain a constant level of sample water in the collector by periodically adding small increments of distilled water to it. However, you could inject PBS into the sampler's inlet throat initially, which would provide the saline environment you want, and then the distilled water automatically provided by our unit would maintain the sample level. If you do this, you might want us to initially set the system up for a 'dry' start-up. Normally, the unit injects a full charge of distilled water immediately upon turn-on to minimize start-up time. With the proposed scenario, you would be providing that start-up fluid charge manually. By the way, the PBS cannot have surfactant in it, since an excessive amount of foam would be created during operation. At least one other customer is doing something like this, but they have not confided details of their procedures to us. You might also want to wash the interior of the SASS from time-to-time so that salts did not build up near the fan entrance, or inside the fan.
What is the function of the software? Is it necessary to have a dedicated computer to the instrument or can we use it purely as a concentrator?
You do not need to be connected to a computer- it is only necessary if you want to change any operating characteristics (such as fluid sample size) from the default levels set at the factory. You also might want to use the software if you were going to use our sampler as part of an automated, computer-controlled system. Otherwise, it is completely self-contained and may be operated with the switches on the instrument.
What are the BioThreat Alert Test Strips?
The BioThreat Alert test strips are lateral flow immunoassay test strips. They are like the test strips commonly used in the US to determine pregnancy. You place a specified amount of fluid (usually 100 uL) on the strip end, and a line will appear at the other end of the strip in about 15-20 minutes if the targeted agent is present in the sample. The test strips are only available to purchasers of our equipment.
What are the limiting factors in how long you can operate the SASS 2300 series air sampler on battery power?
With the standard BA5590/U 15 Ampere-Hr primary battery, the unit will run continuously for about 20+ hours. If you use the AC electrical adapter supplied with the unit, there is no limit to operating time, insofar as electric power is concerned.
How long can SASS 2300 series air samplers operate before replacing make-up water?
The unit automatically adds distilled makeup water from an onboard reservoir that holds about 1200cc, minimum, to offset evaporation. The evaporation rate of course varies with relative humidity and temperature, but as a first approximation, assume that you will evaporate 0.8 cc of water per minute. This means that you can operate continuously for about 24+ hours before the reservoir is exhausted of water. If you want to operate continuously for a longer period, you will need to supplement the internal water reservoir, or add water periodically. For one customer the sampler was fixed in location and we provided a supplemental reservoir that allowed 7 days continuous operation.
Do I need the software to change the initial sampling fluid? Is the software capable of analysis?
No, the software is not necessary at all if you do not want to change the SASS's operating characteristics, or watch it operate on a computer screen. One of the main uses of the computer program is to change operating characteristics, such as sample size, or the system's internal calibration. Some customers like to get into that level of detail, and others are happy to never use the computer link.
Is the instrument autoclavable? Is it sensitive to any particular type of chemicals?
It is made of shock-resistant plastic and is not autoclavable. Sterilization is commonly done using bleach or an oxidizing solution such as hydrogen peroxide. Since it is made in part of plastic components, we do not recommend you use organic solvents without first asking us if they will harm the unit.
Is it necessary to stop the instrument to obtain a sample or can it continue to run while sampling?
Is the top-off of fluid periodic or by sensor feedback?
You can recover a sample at any time. The only downside to collecting a sample while the SASS is operating is that the sample may be a combination of water and air, and the amount of liquid may vary somewhat from sample to sample. The maintenance of a constant fluid sample size is by sensor feedback. We use a proprietary sensor and algorithm in the SASS's electronics to monitor the fluid level, and add water as needed.
Is the carry case necessary for flight transport. Will the box that the instrument came in be sufficient if the need to send the instrument back for repair arises.
The instrument is shipped to you in its carrying case, inside a cardboard box. It is reasonably tough, and could just be shipped back in a cardboard box with packing foam. Or you could ship it back as received, if you prefer.
What is the function of the BioLink RF Data Radio? Is it necessary for the operation of the instrument?
The BioLink is convenient if you want to control, operate or monitor the SASS from a remote location, and don't want to have an RS-232 cable between the SASS and the control computer. It is an accessory, and is not needed for basic operation.
