The 7250LP is available in three different range configurations, each a dual range instrument. Select either the 10 inH20 and 30 inH2O combination, or the 20 inH2O and 60 inH2O or the 35 inH2O and 100 inH2O range combination. Each combination provides a precision to 0.005 % of reading from 10 to 100 % of the higher range. For pressures from 0 to 10 %, the precision is a fixed error equal to 0.005 % of 10 % FS. This unmatched precision is achieved by the unique quartz pressure sensing technology that puts the pressure in direct contact with the quartz element, eliminating mechanical linkages and metal diaphragms. Since this is a differential sensor, the reference side of the 7250LP can be connected to the reference side (low side) of the device under test. Therefore, disturbances due to room drafts, HVAC systems and opening/closing doors, which can have a detrimental effect on the calibration process, are eliminated. The 7250LP provides both unequalled precision and excellent long term stability due to the inherent properties of quartz. For example, the total uncertainty for a 10/30 inH2O range combination over a one year calibration interval is 0.009 % of reading or 0.00015 inH2O (whichever is greater). The 7250LP comes standard with an ISO/IEC 17025 accredited calibration report.
High-speed pressure control
The 7250LP will reach the commanded setpoint in thirty seconds or less into a 15 cubic inch volume, with no overshoot. Once at pressure, the proprietary pulse width modulated valves will maintain the setpoint to within 0.004 % of each range. Therefore, when using the 10 inH2O range in active mode, the control stability is 0.0004 inH2O.
Dual control modes
The 7250LP also provides two user selectable control modes; active and passive. In active mode, the 7250LP is continually maintaining the set point and can compensate for small leaks and pressure changes due to temperature. In passive mode, the user defines a control band and the 7250LP will turn off the controller once it achieves the setpoint within the control band. In a leakfree and temperature-stable system, passive mode can completely eliminate control mode “noise” in the system.
Automating pressure test and calibration
The 7250LP is easy to use and can automate your calibrations in several ways:
Step up/down: for calibrations where the increments are fixed intervals, enter a user-defined step value. The 7250LP increases or decreases the pressure by the step amount with the jog dial—no more lengthy keystroke sequences to program.
Sweep test: For simple exercising routines, as with mechanical gauges, enter a start value, a stop value, and number of times to repeat the cycle. The 7250LP will automatically exercise the device under test prior to the calibration run.
Onboard programs: For frequently used or lengthy calibrations, the 7250LP can store up to 20 user-defined programs/profiles with up to 1000 steps in internal memory.
Computer interface: The 7250LP is provided with both an RS-232 and IEEE-488 interface, and syntax for all Series 7250s follows SCPI protocol for easy programming. COMPASS® for Pressure is available in addition to a LabVIEW® driver, as a free download. As a standard feature, software written for the previous generation Series 7215, 7010 and 6000 instruments is fully supported by the 7250LP. The 7250LP can be set to 510 emulation mode to use software originally written for the DPI 510. Firmware updates can be performed over the RS-232 interface (updates can be downloaded from the web site). A MET/CAL® software driver is available.
Versatility to handle any pneumatic pressure calibration
The 7250LP is versatile enough to handle almost any type of low pressure calibration.
Dual range: The 7250LP has two ranges in one instrument, 10 inH2O and 30 inH2O, or specify the 20 inH2O and 60 inH2O or the 35 inH2O and 100 inH2O range combination. The 7250LP will automatically change ranges to ensure the highest performance at the requested pressure.
Pressure units/scales: The 7250LP includes more than 12 standard units of measure, including inH2O at 4 °C (39 °F), 20 °C (68 °F), and 16°C (61 °F), in Hg at 0 °C (32 °F) and 16 °C (61 °F), kPa, bar, psi, kg/cm3, mm Hg at 0 °C (32 °F), cm Hg at 0 °C (32 °F), and cm H2O at 4°C (39 °F), and two user-defined units.
Head pressure: The 7250LP automatically corrects for head pressure differences.
Autovent and autozero: With a few keystrokes, the 7250LP will vent the test port to atmosphere or automatically zero itself. Protection of the device under test— The 7250LP sets upper and lower pressure limits to ensure protection of the device under test.
The 7250LP can be provided for gauge mode operation, or with:
- Vacuum (negative gauge) mode for bidirectional devices
- Rack mount kit
- COMPASS® for Pressure software
- MET/CAL® software driver
The 7250LP low pressure digital pressure calibrator can easily automate low pressure test and calibration workload. The 7250LP is easy to use, easy to maintain and has the reliability, performance, and features you want.