The 3130 can be used with external 700p/750p pressure modules to allow for better accuracy/uncertainty in some pressure ranges as well as allow absolute mode reading. More info on these can be found here
750p - http://en-us.fluke.com/products/pressure-calibrators/fluke-750p-pressure-modules.html
700p - (Discontinued)
These are made by and can be purchased from our sister company Fluke Industrial. They also sell through many local distributors which might be more convenient for purchasing. Fluke Calibration sales personnel can also quote these with a new 3130.
Here is an example of how the modules are connected by tee'ing them in to typical 3130 pressure plumbing and the electrical connection using cable supplied with the module:
?Some customers will store the modules in the pockets of the 3130 case for convenience as they are fairly small.
Gauge and negative gauge mode are the default measurement modes for the 3130 and covers vacuum (lowest of about -12 PSI) to 300 PSI with a general spec of +- .025% Reading + .01% Full Scale. Since there is a Full Scale component to this spec it might be beneficial to use the 700p/750p modules at low pressures for better accuracy/uncertainty. An extreme example of this would be with a 750p01 module which has a rang of 0 to 10inWa. The accuracy for this range will be much better with this module than the 3130 sensor. The fine adjust knob would be used to carefully set these very low pressures rather than the 3130 electric pump.
To allow absolute mode measurements on the 3130 the only option is to purchase and connect an external 700p/750p absolute module. You would then select this module in the Active Display rather than use the default 3130 internal pressure sensor and the accuracy/uncertainty of the module would be the reference pressure. The 3130 will read the output of the 700p/750p module on its display and would still use it to set pressures during testing. Since the 3130 pump will do sub atmospheric (vacuum) you are still able to do absolute points below your atmospheric pressure. The limit is determined by the 3130 pump which is about 3 PSI absolute (-12 PSI gauge mode spec).