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Typical Q & A about the ACCUSTAT™

How often does the ACCUSTAT™ need to be calibrated?
We suggest that it be calibrated once per year.  It is rare for it to go out of adjustment, but the calibration procedure is an on-site operation. 
What is the calibration procedure?
The procedure is simple and is essentially balancing or equalizing the two probe ports by adjustment of the set screw (potentiometer) to a .000 or equalized reading.
Can the sound alarm be shut off or muted?
The piezo alarm can be muted or the slide switch can be left in the center position for full audio sound monitoring.

Where do I place the ACCUSTAT™?
The recommended placement would be to position it directly outside the area to be monitored.  In the case of a patient isolation room place at eye level outside the room on the wall so anyone entering the room knows if the room is compliant by viewing the actual numerical pressure reading or viewing the green or red lighted LED.

Are there any other placement options?
Viewing convenience is always the first priority so placement can be virtually anywhere. Sometimes for security purposes some facilities position the ACCUSTAT™ above the entrance door. The digital numerical readout is large enough to view from 8 to 10 feet away so visual monitoring is not usually an  issue.
What is the difference between a pressure transducer and an airflow monitor?
There is a big difference as one unit is directly measuring pressure while the other is measuring airflow direction.  Units that list the capability of measuring flow rates of 0.0001” WG are air flow monitors not pressure monitors.  This capability is inconsequential for monitoring isolation rooms because a negative pressure reading as low as -0.0001” is virtually insignificant in the air pressure differential between the controlled space and the referenced space to be compliant.  CDC states .01” WG as a measurement requirement..
Would one unit therefore be more trouble free than the other?
Air flow monitors have a probe head that senses airflow as it moves over it. Since it requires the passage of air to function, and air is laden with particulate matter, there is a buildup of dust particles on the probe that causes false readings and false alarms.  Therefore, periodic maintenance is essential to keep the probe head clean and the unit functioning properly. On the other hand the ACCUSTAT™ is measuring static pressure which is equal in all directions and air quality is not an issue as nothing is passing through its probe tube.  Nothing to be clogged, nothing to affect the actual readings, no false readings or alarms.
What else might cause false alarms with an airflow meter?
As previously stated, since it is measuring airflow especially in a hospital environment many uncontrollable factors will influence the readings.  Elevators on a floor sometimes cause a vacuum as the doors close and they ascend or descend causing a vacuum in the corridor.  Laundry carts passing the probe head create an uncontrolled air movement affecting the air flow direction.  These are just two examples of actual occurrences that were recorded by users of air flow monitors.  In either case the pressure in the room would not have been affected by monitoring with and ACCUSTAT™.
Can the ACCUSTAT™ be placed inside the room?
There is no difference in the readings as two spaces are still being monitored. Although the orientation of the probes change and the tubes need to be reversed if this location is chosen.
Can the ACCUSTAT™ measure positive pressure as well?
The short answer is yes.  There are several options to make this accommodation.  If the room being monitored goes into the positive pressure mode the red LED lights and the alarm activates.  The reading in the window will show positive, but if the room is specified as a “positive pressure room” we can manually reverse the jumper at the factory or it can be easily done in the field to show positive and allow a green LED. Another option is a factory installed keyed switch that can be added and the pressure choice can be manually adjusted to positive or negative with the turn of a key.
What is the accuracy of the ACCUSTAT™?
The ACCUSTAT™ can measure down to 0.001” WG, however the new CDC Guidelines call for -0.01” WG as the minimum negative pressurization reading.  Other units claim to measure pressure down as low as 0.0001” WG.  This pressure differential reading is so low the comparison between spaces is virtually    indiscernible and for all intents and purposes the room pressure would be considered neutral as -0.01” WG is the new guideline.
How long can I expect it to function?
Like any electronic instrument over time the components age and require repair or replacement.  Having said that, we have ACCUSTAT™ monitors in consistent use in many facilities for over 10 years that are still functioning properly.  You can expect to receive many years of trouble free service from the ACCUSTAT™.
What is the measure of readings?
The ACCUSTAT™ is gauged to measure in inches of water or WG, or Pascals. These are the most common gauges for measuring air flow or pressure.
What if I need repairs?
In the unlikely event the ACCUSTAT™ needs repair the face plate housing is removed (with the circuit board attached) and returned to the factory.  The mounting plate can remain on the wall.  It can be returned via UPS or an overnight carrier and returned to you in a day or two.  Always contact the factory at 800-224-9768 for specific instructions before returning monitors for repair.
Can I set my own alarm point?
Yes, it is a user set alarm function and depending upon your requirements it can be set to best monitor your needs.
What is considered a good negative pressure reading?
That is probably the most frequently asked question and a question with many answers. CDC states that -0.01” WG is acceptable to qualify as negatively pressurized.  The higher the pressure number the more exhaust pressure and the better the room will be functioning as an isolation room.  The number you achieve however will be based upon many factors. Some of which would be the amount of supply to the room, the amount of exhaust, if the room is truly sealed, if there are any openings in the ceiling panels or walls where pipes, cables, wires pass through?  Usually no two rooms have the same reading based upon the conditions that govern them.
Where do I place the user alarm setting?
That would depend upon the pressure reading in the room.  If the alarm point is set too close to the actual room pressure you will experience alarms.  Don’t forget CDC states -0.01” is an acceptable negative reading.  Many people set the alarm point at neutral (.000”) or at plus 0.001” reading.  The neutral point gives them warning the plus reading is noncompliance.
Is there a dry contact I can tap into?
Yes, we can pick up any signal by connecting to the dry contact.
At what frequency are the pressure readings upgraded?
The readings are upgraded at one-second intervals.
How do I connect electricity to the ACCUSTAT™?
The ACCUSTAT™ is supplied with a 12 V plug-in transformer with a 4’ low voltage cord with a 2 pin connector.  Simply plug the ACCUSTAT™ transformer into a 115V grounded outlet and it will function.
How easy is it to install?
Installing is an easy process. Determine the location and where you need to position it. Drill a single 1/8” hole through the wall into the room for the probe tube to pass and attach to grommet in stainless steel wall plate (supplied). Attach the four anchors (supplied) to the wall, level housing and attach housing base to wall. Attach probe tube to the back of the unit at port 2 and align housing cover to attached base and secure.
How easy is it to relocate?
The unit can be easily removed and relocated by unscrewing the fasteners, removing the probe tube and disconnecting the transformer.
Is there any delay cycle for quick room ingress or egress?
There is a one-minute alarm delay. If the monitor is activated by the pressure differential reaching the preset alarm point the delay function is triggered. The digital readout will instantaneously read the exact pressure and the LED will turn red indicating that the unit is in the alarm cycle and the area is not compliant but there will be no alarm sounded until one minute passes. This enables staff to enter and exit the room without setting off an alarm that might be construed as a false alarm.
How much power does the ACCUSTAT™ use?
There is very little power consumption, less than 2 watts.
Are there temperature limits on its use?
The ACCUSTAT™’s operating temperature range is between 55 to 105 degrees Fahrenheit.
What are the humidity limits?
The humidity range is between 10% to 94% non-condensing.
Where else can I use the ACCUSTAT™ monitor?
There are a number of rooms in the hospital that require negative or positive pressure.  Consult our web-site at for rooms requiring Negative/Positive Pressure.
What is the power operating range?
The ACCUSTAT™ operates between 12-16V AC or DC @ 50/60 Hz
If I have an anteroom where should the ACCUSTAT™ be placed?
There is a convenience factor in placing the ACCUSTAT™ in the corridor thereby allowing personnel the ability to view and know the room status prior to entering.  This usually requires an extended probe tube passing through the anteroom to the isolation room.  As long as the tube isn’t bent or kinked a 10-12 ft. run isn’t a problem.  If you choose to place the ACCUSTAT™ in the anteroom that will work as well, but there still needs to be pressure comparison between the controlled space (isolation room) and the referenced space (anteroom).  The anteroom pressure wise should be slightly negative to the hall or corridor.
How long of a probe tube can I run?
The probe tube can be of plastic, vinyl or a copper tube. Some installations have run tubes 12-15 feet.  As long as there are no bends, compression or leakage, the ACCUSTAT™ can easily measure two spaces unattached.

Is there a portable version of the ACCUSTAT™ available?
Yes, the ACCUSTAT™ also is available in a portable version (P2) battery operated and powered by a Ni-MH nickel metal hydride rechargeable battery.  It is ideal for monitoring remote locations or when various rooms need to be checked, and daily monitoring isn’t required.  Battery life is over 48 hours on a single charge.  For more information on the portable units, please visit our website at:

Can the ACCUSTAT™ be connected to our Building Management System?
Yes, the ACCUSTAT™ can be equipped with an optional module that allows it to communicate with your Management System as long as your system can connect to a 4-20 milliamp signal.
Can the ACCUSTAT™ be monitored from a remote location?
Yes, with the addition of the remote monitoring panel up to 6 rooms can be monitored at a single convenient location, usually the nurse’s station.  This allows anyone to know the status of any room at any one time.  The panel is a series of green and red LED’s that corresponds to the individual rooms.  If any room goes into alarm mode the red LED signifying that location will activate along with the audible alarm (can be muted).  The remote is powered by a single 16V plug-in transformer that also powers all the ACCUSTAT™’s connected to it.  The ACCUSTAT™’s at each location still perform and provide the digital readout information in addition to all the standard options and features.
Is there a tamperproof switch to prevent unauthorized tampering?
Yes, the ACCUSTAT™ has a keyed switch on the top of the housing.  The unit can be turned on or off with a special removable key to prevent unauthorized tampering.
How loud is the alarm?
The piezo alarm is 75 dB @ 3 feet. The alarm has a mute feature.

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