Series-HM35

Supported Applications

The Dwyer Series HM35 Precision Digital Pressure Manometer is designed to measure absolute pressure, differential pressure, gage pressure, and vacuum. The instrument supports data logging functions capable of storing up to 10,742 readings for subsequent analysis via PC transfer using an IR serial port interface.

Documented service compatibility includes air and compatible gases. The large graphical backlit LCD display (128 x 64 points) allows users to view trends in data as well as peaks and valleys directly on the instrument face.

Operating Conditions & Performance

The Series HM35 operates within an ambient temperature range of 32 to 122°F (0 to 50°C) with a permissible storage temperature range of -4 to 140°F (-20 to 60°C). Humidity limits are defined as maximum 95% RH non-condensing. The instrument enclosure carries an IP54 (NEMA 3) rating.

Accuracy specifications vary by model configuration, offering ±0.20% FS ±1 digit, ±0.10% FS ±1 digit, or ±0.05% FS ±1 digit. These accuracy values include linearity, hysteresis, and repeatability. Higher accuracies (±0.05% FS) are available on the 0 to 28 in w.c. range or higher.

Power is supplied by three 1.5 V AA alkaline batteries (installed functional, user replaceable). The unit can also operate on external power from 6 to 9 VDC. Current consumption is specified as 25 mA without the backlit display, IR interface, or buzzer active.

Measurement Ranges and Overpressure Limits

The series supports multiple pressure ranges with specific overpressure limits per model:

• Hose 4/6 mm connection: ≤ 7.5 bar range available in the family manual context.
• NPT 1/8" internal thread: Ranges from 0 to 2.5 kPa up to 0-100 kPa (0 to 14.5 psi) are documented with overpressure limits ranging from 50 in w.c. to 600 in w.c., and up to 58 psi for higher ranges.
• Specific Model Limits:

• HM3531DLB300: Range 0 to 10 in w.c. (0-2.5 kPa), Over Pressure 50 in w.c.
• HM3531DLC300: Range 0 to 28 in w.c. (0-7 kPa), Over Pressure 140 in w.c.
• HM3531DLE300: Range 0 to 80 in w.c. (0-20 kPa), Over Pressure 600 in w.c.
• HM3531DLF300: Range 0 to 120 in w.c. (0-30 kPa), Over Pressure 600 in w.c.
• HM3531DLG300: Range 0 to 200 in w.c. (0-50 kPa), Over Pressure 58 psi.
• HM3531DLH300: Range 0 to 14.5 psi (0-100 kPa), Over Pressure 58 psi.

Configuration Options

The Series HM35 is configurable across several dimensions including pressure range, accuracy class, and process connection type. The wetted materials are specified as 18/8 stainless steel. Process connections include Hose 4/6 mm or 1/8" NPT.

Available Accessories

• HM35-1: Communication software key.
• HM35-2: Infrared RS-232 serial adaptor, required to download stored data to a PC.
• HM35-3: External power converter with U.S. plug adaptor (input 100 to 240 VAC, 50/60 Hz).

Data Logging and Communication Options

• Memory Capacity: Stores up to 10,742 readings.
• Recording Intervals: Adjustable from 1 s to 24 hrs or manual trigger.
• Interface: IR serial port supporting SCPI commands for PC communication.

Calibration Options

• New units include a data report/calibration report. A NIST traceable calibration certificate is available via order code NISTCAL-MD1.

Key Product Differences

The Series HM35 model numbering follows the pattern HM3531DL<range_code><accuracy_code>. For example, HM3531DLC100 denotes a 0 to 28 in w.c. range with 0.05% accuracy.

Variations exist primarily in the pressure measurement ranges and associated overpressure limits as detailed in the model chart. Accuracy levels are distinguished by specific digits within the model code: changing the 10th digit from a '3' to a '1' indicates ±0.05% FS, while '2' or '6' may indicate other accuracy classes depending on availability and range constraints.

Physical dimensions for the instrument are listed as height 7-7/8 [200.03], width 3-11/16 [93.66], and depth 1-9/16 [39.69]. The unit weighs 10.5 oz (300 g).