Solution for Measuring Water Pressure and Differential Pressure in HVAC Systems – Dwyer Pressure Sensors Series 626, 628, 629C, 629HPL

Posted on: 09/06/2025

Water pressure sensors are devices used to measure and monitor the pressure or differential pressure of liquids in systems such as water supply, HVAC, wastewater treatment, and industrial automation. These sensors convert pressure into electrical signals (commonly 4–20 mA or 0–10 V), allowing data to be transmitted to a central controller or PLC for accurate and safe system operation and alerts.

Dwyer Instruments (USA) is one of the world’s leading manufacturers in the field of measurement and control devices. Among their products, the pressure and differential pressure sensors in series 626, 628, 629C, and 629HPL are widely used in industrial, water treatment, HVAC, and automation systems.

1. What is a Dwyer Pressure Sensor?

A Dwyer pressure sensor measures absolute, differential, or gauge pressure in gas, steam, or liquid systems. The pressure is converted into an electrical signal (typically 4–20 mA or 0–10 V) for monitoring, alarms, or automated control.

Dwyer offers specialized models for measuring water and fluid pressure:

Series 626 – Designed for liquid pressure, rugged stainless-steel housing, ideal for industrial and HVAC use.
Series 628 – Suitable for both liquid and gas pressure, high stability and accuracy, used in medium to high pressure environments.
Series 629C – Designed for non-corrosive liquids and water, wide measuring range, features modern integrated electronics.
Series 629HPL – High precision (High Performance Level) sensor for demanding applications like chilled/hot water systems and complex fluid transport systems.

These sensors are widely applied in HVAC, water supply systems, booster pumps, boiler monitoring, and automated industrial control systems.

2. Overview of Features and Advantages of Dwyer Pressure Sensor Series

2.1. Series 628 – Industrial Pressure Sensor

Key Features:

High Accuracy: 1.0% FS (Full Scale), 0.5% RSS (Root Sum Square).
Protective Housing: NEMA 4X (IP66) rated, dustproof and waterproof for harsh environments.
Wetted Materials: 316L stainless steel – corrosion-resistant, suitable for various liquids and gases.
Power Supply: 10–30 VDC (4–20 mA); 13–30 VDC (0–10 VDC).
Applications: Pump systems, irrigation, submersible pump control, industrial pressure monitoring.

2.2. Series 629C – Differential Pressure Sensor

Key Features:

Wet Differential Pressure: Suitable for both liquids and gases, accuracy ±0.5% FS.
Protective Housing: NEMA 4X (IP66) rated.
Output Options: 4–20 mA (2-wire), or 0–5 VDC, 1–5 VDC, 0–10 VDC, 2–10 VDC (3-wire).
Optional LCD Display: Real-time pressure display, no separate power required.
Applications: Filters, heat exchangers, pumps, coils, chillers, HVAC systems.

2.3. Series 629HPL – Differential Sensor for High Static Pressure

Key Features:

High Static Differential Pressure: Accurate ±0.5% FS, suitable for high-pressure systems.
Output Options: 4–20 mA or 0–10 VDC.
Applications: Industrial processes requiring precise differential measurements under high static pressure.

3. Comparison Table of Pressure Sensor Series

Series	Accuracy	Pressure Type	Static Pressure	Output Signal	LCD Display	Key Applications
628	1.0% FS	Absolute/Gauge	Unlimited	4–20 mA, 0–10 VDC	No	Pumps, irrigation, industry
629C	±0.5% FS	Wet Differential	Unlimited	4–20 mA, 0–5/1–5/0–10/2–10 VDC	Optional	Filtration, HVAC, exchangers
629HPL	±0.5% FS	High Static Differential	High	4–20 mA, 0–10 VDC	No	High static pressure industrial setups

4. Choosing the Right Model by Range and Output Signal

The table below lists popular models by pressure range (0–10 bar to 0–16 bar), output signal (4–20 mA or 0–10 V), and product series, allowing engineers and system designers to select quickly and accurately.

No.	Sensor Type	Pressure Range	Output Signal	Series	Model Code
1	Water Pressure Sensor	0–10 bar	4–20 mA	626	626-75-GH-P1-E1-S1
2	Water Pressure Sensor	0–10 bar	0–10 V	626	626-75-GH-P1-E1-S5
3	Water Pressure Sensor	0–16 bar	4–20 mA	626	626-90-GH-P1-E1-S1
4	Water Pressure Sensor	0–16 bar	0–10 V	626	626-90-GH-P1-E1-S5
5	Water Pressure Sensor	0–10 bar	4–20 mA	628	628-75-GH-P1-E1-S1
6	Water Pressure Sensor	0–10 bar	0–10 V	628	628-75-GH-P1-E1-S5
7	Water Pressure Sensor	0–16 bar	4–20 mA	628	628-90-GH-P1-E1-S1
8	Water Pressure Sensor	0–16 bar	0–10 V	628	628-90-GH-P1-E1-S5
9	Differential Pressure Sensor	—	4–20 mA	629C	629C-05-CH-P1-E1-S1
10	Differential Pressure Sensor	—	0–10 V	629C	629C-05-CH-P1-E1-S3
11	Diff. Pressure Sensor + LCD	—	4–20 mA	629C	629C-05-CH-P2-E1-S1-3V
12	High Static Diff. Sensor	—	4–20 mA	629HPL	629HLP-06-P2-S1
13	High Static Diff. Sensor	—	0–10 V	629HPL	629HLP-06-P2-S5

Notes:

"P1" refers to standard pressure connection type.
"E1" indicates standard power supply.
"75" = 0–10 bar; "90" = 0–16 bar.
629C = general wet differential pressure sensor.
629HPL = for high static pressure differential measurement.
"GH" = robust design suitable for water and harsh environments.

5. DLK – Authorized Distributor of Dwyer Pressure Sensors in Vietnam

DLK – Long Khanh Electrical Technical Trading Co., Ltd. is an official distributor of Dwyer Instruments in Vietnam, offering the full range of pressure sensor products including SERIES 629, 629HPL, and 629C.

Why choose DLK: