DR pressure regulators with inlet up to 25 bar

New series

Pressure regulators of the DR series by KNOCKS FLUID-Technik reduce the pressure of compressed air from the air network – up to 25 bar – to the working pressure required by the machine, the tool or an entire branch of the air network. They keep the set pressure constant even when the network pressure fluctuates and air consumption changes.

They are diaphragm regulators with secondary venting, and a pressure gauge is included. Five body sizes cover flow rates of 1,750 to 16,500 l/min and threads from G 1/4" to G 1 1/2". In function, they correspond to the EWO 280 and 406 regulators, but they are also designed for higher flow rates and larger pipework.

What the DR regulators offer

• secondary venting – you can reduce the outlet pressure even with no air being consumed
• flow rates of 1,750 to 16,500 l/min in five body sizes
• pressure gauge included, with a range to match the control range
• control ranges 0.5–10 / 0.5–16 bar
• inlet pressure up to 25 bar (smallest size BG 1 up to 16 bar)
• sizes BG 1 to BG 3 can also be mounted in a control panel (M20 × 1.5 thread)
• for compressed air as well as neutral gases
• zinc die-cast body (BG 5 and BG 7 aluminium), NBR diaphragm and seals, operation from −10 to +60 °C

Five body sizes

The body size determines the flow rate. Within one size, all threads have the same flow rate – they differ only in the connection.

Flow rate according to the manufacturer KNOCKS. Dimensions: length between the connections × overall height including the handwheel or T-handle. In size BG 3, the G 1/2" version is 82 mm long, the G 3/4" and G 1" versions 90 mm.

All DR regulators

DR regulators or EWO 280 and 406?

In function, they are the same: a diaphragm regulator with secondary venting and pressure gauge, inlet up to 25 bar. They differ in sizes and ranges. For flow rates above 5,330 l/min or G 1 1/4" and G 1 1/2" pipework, choose DR. For the 0.5–3 and 0.5–6 bar ranges or operation above +60 °C, there are EWO regulators 280 and 406.

Flow rates of both series according to the manufacturers; for EWO at an inlet pressure of 8 bar, an outlet pressure of 6 bar and a pressure drop of 1 bar.

How to choose a DR regulator

1. Size according to air consumption. Add up the air consumption of the machines and tools downstream of the regulator. BG 1 handles 1,750 l/min, BG 2 2,200 l/min, BG 3 5,000 l/min, BG 5 11,000 l/min and BG 7 16,500 l/min. At a lower network pressure, less air flows through – in that case choose a larger size.
2. Inlet pressure. Sizes BG 2 to BG 7 withstand up to 25 bar in the air network, the smallest BG 1 (DR 11 and DR 12) only 16 bar. If there is more than 16 bar in the network and a low flow rate is sufficient, choose DR 22 or DR 23.
3. Control range according to the working pressure. Choose a range whose upper limit is above the pressure you want to set. For 6 bar, the 0.5–10 bar range is suitable; for 12 bar, the 0.5–16 bar range. In a smaller range, the pressure can be set more finely.
4. Thread according to the pipework. The flow rate is determined by the body size, not by the thread: G 1/2" comes in sizes BG 2 and BG 3, G 3/4" and G 1" in sizes BG 3 and BG 5.

Example: a workshop needs 6 bar for tools with an air consumption of 4,000 l/min, there are 10 bar in the air network and the pipework has a G 3/4" thread. Size BG 3 with the 0.5–10 bar range is sufficient; this is DR34. At an air consumption of 9,000 l/min, it would be size BG 5, DR54.

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How a regulator with secondary venting works

1. With the handwheel or T-handle you tension the spring. The spring presses on the diaphragm, which opens the valve – air flows from the inlet to the outlet.
2. The outlet pressure pushes on the diaphragm against the spring. When it reaches the set value, the valve partially closes and only as much air flows through as is being consumed.
3. The outlet reacts only slightly to pressure fluctuations in the network: according to the manufacturer’s graph, a set pressure of 2 bar moves by no more than about 0.1 bar when the inlet pressure changes between 3 and 10 bar.
4. When you reduce the set pressure or the outlet pressure rises, the diaphragm opens the vent hole and the excess air escapes.

Flow curves

The manufacturer’s graphs show how the outlet pressure drops as the flow rate increases at an inlet pressure of 8 bar. The lines start at a set pressure of 2, 4 and 6 bar. The flatter the line, the more stable the pressure at high air consumption.

Installation and adjustment

• install a compressed air filter upstream of the regulator – dirt from the pipework would damage the valve seat
• connect the regulator with its inlet to the air network and its outlet to the consumers
• the pressure gauge shows the outlet pressure; the pressure gauge connection has a G 1/4" thread
• set the pressure from below: loosen the handwheel or T-handle to below the required value, then tighten it until the pressure gauge shows the required pressure
• fix the regulator to a wall or frame with a mounting bracket; sizes BG 1 to BG 3 also have a panel mounting thread (M20 × 1.5)

Spare parts and accessories

The diaphragm with the control piston wears over time – replace the kit and the regulator will keep on working. Add a bracket when you mount the regulator on a wall or frame. For panel mounting, there is a panel nut and a panel mounting bracket.

Sizes BG 5 and BG 7 have no panel thread; they are fixed to a wall with a bracket.

You will find all parts for the regulators in the category spare parts and accessories for pressure regulators.

Series specifications

What is the difference between DR regulators and EWO 280 and 406?

In function, they are the same – diaphragm regulators with secondary venting and pressure gauge, inlet up to 25 bar. DR additionally offers sizes BG 5 and BG 7 for flow rates of up to 16,500 l/min and G 1 1/4" and G 1 1/2" threads. The 280 and 406 series also have the 0.5–3 and 0.5–6 bar ranges and withstand temperatures of up to +90 °C.

Why do DR 11 and DR 12 only withstand 16 bar at the inlet?

The manufacturer specifies the smallest size BG 1 for an inlet pressure of up to 16 bar, the other sizes for 25 bar. If there is more than 16 bar in the network, choose DR 22 (G 3/8") or DR 23 (G 1/2").

Which control range should I choose?

One whose upper limit is above the required pressure. For 6 bar, the 0.5–10 bar range is suitable; for 12 bar, the 0.5–16 bar range. In a smaller range, the pressure can be set more finely.

Is the pressure gauge included?

Yes. For the 0.5–10 bar control range, the pressure gauge has a range of 0–16 bar; for the 0.5–16 bar control range, 0–25 bar.

What is secondary venting?

The regulator can release air from the outlet by itself. When you reduce the set pressure, the excess air escapes through the vent hole and the pressure drops immediately, not only once air is consumed. A short hiss is therefore normal.

Can the DR regulator be mounted in a panel?

Sizes BG 1 to BG 3 can – they have a panel thread (M20 × 1.5) for a panel nut. A panel mounting bracket is fixed via the same thread. Sizes BG 5 and BG 7 are fixed to a wall with a bracket.

Can I use the regulator for a gas other than air?

The manufacturer specifies it for compressed air and neutral gases. For any other gas, please ask us before ordering.

Technical data according to the manufacturer KNOCKS FLUID-Technik. Flow curves at an inlet pressure of 8 bar.

You will find more regulators in the category air pressure regulators.