The BT-Maric constant flow valves (sometimes called flow regulators, flow regulation valves, flow limiters and flow control valves) maintain a fixed, pre-set (non-adjustable), constant flow rate, regardless of pressure. BT-Maric flow restrictors will keep the flow rate of a liquid in a pipe system to a specified value, regardless of pressure variations.
Bertfelt is the leading manufacturer of BT-Maric constant flow valves for industrial use.
Bertfelt offers a complete range (flow rates from 0,15 L/min to 8.854 L/min) of precise constant fluid flow valves for industrial use
– that saves water and makes products and processes more efficient.
We also offer Tailor-made OEM solutions in order to meet our OEM Manufacturers customer challenges.
Our flow limiters are used in many different industries and applications such as process and food industries, water treatment, pump & filter protection, fire fighting, marine applications, irrigation and farming etc.
Applications
The BT-Maric Constant Flow Valves are available
in 3 standard connections:
Easy to install
BT-Maric Threaded Constant Flow Valves are designed for pipes from 1/8″ up to 2″ and regulate flow rate from as low as 0,15 L/min up to 342 L/min.
Cost effective and compact!
BT-Maric Inserts are designed to be fitted inside existing pipe work or other equipments. They control flow rates up to 233 L/min.
For larger flow rates!
BT-Maric Wafers are designed to be placed between flange for pipe sizes between DN20 up to DN300. They control flow rates up to 8.854 L/min.
BT-Maric constant flow valves utilize a flexible rubber control O-ring with an orifice diameter that responds instantly to fluctuations in water pressure.
As pressure differential increases, the orifice diameter reduces to maintain the pre-set flow rate.
Likewise, as pressure reduces, the orifice opens up to maintain the pre-set flow rate.
The ring has a larger opening at low pressure.
At high pressure the ring is pressed against the conical body. The ring’s opening reduces and the flow remains constant.
The BT-Maric flow control valve is designed to deliver a pre-determined constant flow rate of water and similar media regardless of pressure variations within a certain pressure range. The pressure range depends on the type of valve used.
The BT-Maric constant flow valve has an effect on the pressure, but is not designed to control the pressure in your system.
The control flow valve has no external actuation and is not adjustable after installation.
BT-Maric constant flow valves do not work with gas or air.
BT-Maric constant flow valves utilize a flexible rubber control O-ring with an orifice diameter that responds instantly to fluctuations of the pressure exerted. When the pressure increases the o-ring is pressed down in the conical seat and the orifice of the o-ring decreases in size in such a way that the flow remains constant at the pre-set nominal rate, and vice versa. In this way, the pre-set nominal flow rate is always kept constant regardless of the pressure variations.
BT-Maric constant flow valves will help you:
No, only for water and similar liquids.
Bertfelt’s full range of BT-Maric constant flow valves functions as a family of mechanical flow regulators, covering pipe sizes from DN6 threaded fittings up to DN300 wafer flanges. The same passive O-ring principle applies across every body type — what changes is the mounting and the flow-rate envelope.
For low-flow applications under 5 L/min, the threaded body offers the highest accuracy. For mid-range industrial pipework, wafer flow regulators slot between standard flanges. For OEM integration where a separate body would add cost or complexity, insert flow regulators press-fit directly into existing housings. All three share the same characteristic: a fixed, factory-set flow rate that holds regardless of upstream pressure variation, with no electronics, no calibration, and no scheduled maintenance.
Engineers specifying flow regulation in water and industrial systems use the BT-Maric family because the mechanism is genuinely passive — failure modes that affect electronic control valves (signal drift, actuator wear, power loss) simply don’t apply.
