Two Models:
OM250, for boilers up to 250 psi
OM650, for boilers up to 650 psi

Features include:
1. Inlet connection: 3/4" NPT
2. Adjustment pinion, removable for security
3. Index to locate orifice hole for required blowdown rate
4. Sediment chamber with stainless steel filter screen keeps large solids from clogging orifices
5. Drain valve to flush solids from the sediment chamber
6. Drain connection: 1" NPT for model OM250, and 1-1/4" NPT for model OM650
7. Orifice plate with 17 different hole sizes

The madden orifice meter gives the boiler operator precise repeatable control of the continuous blowdown flow rate. 17 different hole sizes are drilled in the stainless steel orifice plate. Each hole is precision drilled to a diameter that will produce the flow. By selecting a larger hole the continuous blowdown flow is increased, or by selecting a smaller hole number on the index band the blowdown is reduced. Four different orifice plates (1A, 2A, 3A, and 4A) are available to provide a blowdown flow range suitable for the boiler operator to maintain the target boiler water quality level.

The boiler must have a continuous blowdown skimmer pipe installed inside the boiler drum, with the opening for the pipe within 6" of the normal water level in the boiler drum. The Madden Orifice Meter may be mounted near the boiler or near a continuous blowdown heat recovery system. The constant blowdown flow provided be the Madden Orifice Meter makes it an ideal device for use in conjunction with a blowdown heat recovery system.

The Madden Orifice Meter has been in production for almost 50 years. The units are generally used on industrial boilers from 200 HP up to over 100,000 PPH steam production, operating pressures from 50 psi up to 650 psi. One unit is required for each boiler. The meter can be utilized as the sole flow control device or piped in parallel with a conductivity sensing blowdown control. The units are also used with non-fired boilers and reboilers used in refineries. The Madden Orifice Meter is guaranteed for up to 10 years against damage from cutting, wire drawing, or other distortion in the orifice plate.
 

The index slot in the steel selector disc exposes the desired orifice on the orifice plate for service. The selector disc rotates when the adjustment key is turned from one index number to another. The disc has a Stellite surface hardening coating and is lapped to the same finish and flatness as the mating orifice plate to insure a leak free seal.

Type 420 stainless steel material is used to make the orifice plate. The plate is drilled with 17 holes of increasing size. Call or Email for us for flow charts to find out the actual hole sizes and the blowdown for each hole at various boiler pressures. The orifice plate is heat treated to 500 brinnel hardness and lapped to a mirror finish with a tolerance of three light bands (.00003"). The lapped finish prevents high pressure water from leaking through any orifice but the one selected.