Data Sheet for Product

ManualsBrandsSiemens ManualsPressostats (pressure)EU Declaration of Conformity QBM81-x / QBM9903-x

QBM81-…

Technical Instructions

Document No. CA1N1552E-P25

November 24, 2003

Differential Pressure Switch

Description

Differential pressure switch for monitoring air pressure in HVAC systems.

Features

• Monitors air filters, airflow and fan belts

• Can be used to monitor pressure in clean rooms, kitchens, etc.

• Easy to mount

Application

The QBM81-... Differential Pressure Switches are used to monitor differential pressure,

underpressure and overpressure in HVAC installations. By measuring differential

pressure, they monitor the state of air filters, prevailing airflows, damaged fan belts and

overpressure in clean rooms, kitchens, etc. They are also used to monitor differential

pressure and positive and negative relative pressure in HVAC systems.

Product Numbers

There are three differential pressure switches available that measure various pressure

ranges:

Table 1. Product Numbers.

Product Number Pressure Range (Inches WC)

QBM81-3 0.08 to 1.20

QBM81-5 0.20 to 2.00

QBM81-10 0.40 to 4.00

Ordering

If required, FK-PZ... duct probes must be ordered separately.

When placing an order, specify the quantity, product number and description.

Example:

1 QBM81-5 Differential Pressure Switch and one set of FK-PZ2 duct probes

Siemens Building Technologies, Inc.

Summary of content (5 pages)

PAGE 1
Technical Instructions Document No. CA1N1552E-P25 November 24, 2003 QBM81-… Differential Pressure Switch Description Differential pressure switch for monitoring air pressure in HVAC systems. Features • Monitors air filters, airflow and fan belts • Can be used to monitor pressure in clean rooms, kitchens, etc. • Easy to mount Application The QBM81-... Differential Pressure Switches are used to monitor differential pressure, underpressure and overpressure in HVAC installations.
PAGE 2
Technical Instructions Document Number CA1N1552E-P25 November 24, 2003 Operation QBM81-… Differential Pressure Switch The differential pressure between the two pressure connections deflects a springloaded diaphragm. This special diaphragm ensures long-term stability of switching points. Each type is engraved with individual scales for highly accurate adjustment. The options for adjustment are shown in Figure 2. Switch State XD 1 2 3 SMIS0077R1 1 1 2 3 0 ∆p W Figure 1. Operation Diagram.
PAGE 3
QBM81-… Differential Pressure Switch Accessories Technical Instructions Document Number CA1N1552E-P25 November 24, 2003 For difficult conditions or cases where high-precision measurements are required, two other kits are available: FK-PZ1 Set of two duct probes (nickel-plated iron) with rubber grommet FK-PZ2 Set of two duct probes (aluminum) with aluminum mounting rosettes and four mounting screws Mounting Notes Mounting instructions are enclosed with the pressure switch.
PAGE 4
Technical Instructions Document Number CA1N1552E-P25 November 24, 2003 QBM81-… Differential Pressure Switch Housing Cover Diaphragm Mounting bracket Duct adapters Tubing Fiberglass reinforced polycarbonate Polycarbonate Silicone (low-swell rubber, no ABS) Sheet-steel (galvanized) ABS PVC, soft Connections Electrical connection Cable entry Pressure connections 3 screw terminals PG11 cable gland Male, ø 0.24-inch Weight and Dimensions Weight (including packaging) Dimensions 0.42 lb.
PAGE 5
QBM81-… Differential Pressure Switch Technical Instructions Document Number CA1N1552E-P25 November 24, 2003 Dimensions All dimensions in inches (millimeters) 3.52 (89.4) 1.75 (44.4) 0.98 (25) 1.58 (40) 3.60 (91.4) 0.87 (22) 1 2.01 (51) 5 2 3 ø0.24 (ø6.2) 3.47 (88) 0.75 (19) P2 ø3.19 (ø81) P1 SMIS0081R1 4 Legend: 1 Mounting bracket 2 P1 connection, higher pressure 3 P2 connection, lower pressure 4 Pressure differential scale (factory-sealed with paint) 5 Setpoint knob Figure 5.