Braukmann F76S Water Filters and MV876B Automatic-Backwash Controls

Application

The F76S is a high-flow capacity water filter designed for point-of-entry (POE) use in residential or commercial water systems. It effectively removes sediment and debris. As a prefilter, the F76S protects other water system components, such as specialized treatment devices (e.g., taste/odor filters, reverse osmosis systems), fixtures, and appliances. Its flow rate, filtering capacity, and ease of cleaning make it suitable for demanding applications.

The MV876 Automatic-Backwash Control is an optional accessory. It attaches to the drain valve and is programmed by the user to automatically perform backwashing at pre-set intervals.

Features

F76 Water Filter

• Built-in backwash impeller ensures efficient cleaning, even with supply pressures as low as 22 psi.
• Increased flow capacity on 1/2 in. to 1 1/4 in. models reduces pressure drop.
• Robust backwash mechanism.
• No shut-off or disassembly is required for cleaning.
• During backwash, the F76S continues to supply filtered water uninterrupted via a secondary screen.
• A memory ring indicates when the next manual backwash is due.

MV876 Automatic-Backwash Control

• The MV876B1018 bayonet fitting simplifies upgrading to automatic backwash.
• Features 16 field-selectable backwash intervals, ranging from every four minutes to once every three months, eliminating the need for an external timer.
• Connections for external control on the MV876B allow integration with automated systems and differential pressure control.
• The MV876B can be manually turned to initiate backwash.
• Includes a battery (AA) backup to ensure completion of the backwash cycle during power loss.

Specifications

F76S Water Filters

Models: Water filters with 100-micron screens and various hose connections.

• F76S1007: 1/2 in. sweat and NPT threaded tailpieces.
• F76S1015: 3/4 in. sweat and NPT threaded tailpieces.
• F76S1023: 1 in. sweat and NPT threaded tailpieces.
• F76S1031: 1 1/4 in. sweat and NPT threaded tailpieces.
• F76S1049: 1 1/2 in. NPT threaded tailpieces.
• F76S1056: 2 in. NPT threaded tailpieces.

Dimensions: Refer to Figure 1 for F76S Dimensions.

Materials of Construction:

• Body: Brass
• Screen: Stainless Steel
• Internal Construction: Acetal Copolymer
• Seals: NBR
• Ball Valve: Brass with PTFE Seals
• Sump: Engineered Plastic (Bronze sump also available)

Inlet Pressure:

• Minimum: 22 psi (with unrestricted backwash discharge)
• Maximum: Plastic Sump: 232 psi; Bronze Sump: 400 psi. (Pressures above 200 psi require an inlet pressure gauge with a wider range.)

Differential: Maximum Recommended: 42 psi.

Operating Pressure Drop: Maximum Recommended: 3 psi (with clean screen).

Maximum Temperature: Plastic Sump: 104°F (40°C); Bronze Sump: 158°F (70°C).

Pipe Sizes: 1/2, 3/4, 1, 1 1/4, 1 1/2, and 2 inches.

Connections: Union on inlet and outlet; External NPT threaded or sweat.

Capacity: Refer to Table 1 for Gallons Per Minute (gpm).

Screen Sizes: Shipped with device: 100 microns. Available Kits: 20, 50, and 200 microns.

MV876 Automatic-Backwash Controls

MV876B1018: Features a bayonet-mounted shaft for a 24 Vac motor and timer, replacing manual ball valve control for automatic backwash at preprogrammed intervals. A 24V transformer is not included. For use with F76S Filters only.

Specifications:

• Power: 4 VA
• Current: 170 mA
• Voltage: 24 Vac
• Cycle Time: Approximately 20 seconds
• Timer: Variable (Refer to Table 2 for selections)

Accessories for F76S (and other noted items)

Sump O-Ring Kits:

• 0900747: For 1/2 to 1 1/4 in. F76S (10 O-Rings)
• 0900748: For 1 1/2 to 2 in. F76S (10 O-Rings)

Gasket Packages: (10 gaskets per package)

• 0901444: For 1/2 in. and 3/4 in. F76
• 0901445: For 1 in. F76
• 0901446: For 1 1/4 in. F76
• 0901447: For 1 1/2 in. F76
• 0901448: For 2 in. F76

Screen Inserts (Double Spin):

• AF11DS-1/2A: 100 microns, for 1/2 to 3/4 in. F76S
• AF11DS-1A: 100 microns, for 1 to 1 1/4 in. F76S
• AF11DS-1/2B: 20 microns, for 1/2 to 3/4 in. F76S
• AF11DS-1B: 20 microns, for 1 to 1 1/4 in. F76S
• AF11DS-1/2C: 50 microns, for 1/2 to 3/4 in. F76S
• AF11DS-1C: 50 microns, for 1 to 1 1/4 in. F76S
• AF11DS-1/2D: 200 microns, for 1/2 to 3/4 in. F76S
• AF11DS-1D: 20 microns, for 1 to 1 1/4 in. F76S

Screen Inserts (Without Double Spin):

• AF11S-1/2A: 100 microns, for 1/2 to 3/4 in. F76S
• AF11S-1A: 100 microns, for 1 to 1 1/4 in. F76S
• AF11S-1/2B: 20 microns, for 1/2 to 3/4 in. F76S
• AF11S-1B: 20 microns, for 1 to 1 1/4 in. F76S
• AF11S-1/2C: 50 microns, for 1/2 to 3/4 in. F76S
• AF11S-1C: 50 microns, for 1 to 1 1/4 in. F76S
• AF11S-1/2D: 200 microns, for 1/2 to 3/4 in. F76S
• AF11S-1D: 20 microns, for 1 to 1 1/4 in. F76S
• AF11S-11/2A: 100 microns, for 1 1/2 to 2 in. F76S
• AF11S-11/2B: 20 microns, for 1 1/2 to 2 in. F76S
• AF11S-11/2C: 50 microns, for 1 1/2 to 2 in. F76S
• AF11S-11/2D: 200 microns, for 1 1/2 to 2 in. F76S

Filter Sump Kits:

• KF11S-1A: Clear Plastic, for 1/2 to 1 1/4 in. F76S
• KF11S-11/2A: Clear Plastic, for 1 1/2 to 2 in. F76S
• FT09RS-1A: Bronze, for 1/2 to 1 1/4 in. F76S
• FT09RS-11/2A: Bronze, for 1 1/2 to 2 in. F76S

Ball Valve Assembly:

• KH11S-1A: For 1/2 to 2 in. F76S (Includes Ball Valve, Ball Valve O-Ring)

Pressure Gauges:

• M76K-200: 200 psi maximum
• M76K-400: 400 psi maximum

Tailpieces: (Sweat or NPT threaded)

• U76S5007 (1/2 in.), U76S5015 (3/4 in.), U76S5023 (1 in.), U76S5031 (1 1/4 in.), U76S5039 (1 1/2 in.), U76S5047 (2 in.)
• U76T1004 (1/2 in.), U76T1014 (3/4 in.), U76T1022 (1 in.), U76T1030 (1 1/4 in.), U76T1038 (1 1/2 in.), U76T1046 (2 in.)

Union Nuts: N/A

Sump Wrench:

• ZR10K-34: For 1/2 in. and 3/4 in. F76S
• ZR10K-1: For 1 in. and 1 1/4 in. F76
• ZR10K-11/2: For 1 1/2 in. and 2 in. F76; also for 1/2 in. and 3/4 in. F76A,G

Table 1: Capacity in Gallons Per Minute (gpm)

Flow Volume for 15 sec backwash at 60 psi inlet: 3.2 gpm (1/2 in.), 3.2 gpm (3/4 in.), 4.0 gpm (1 in.), 4.0 gpm (1 1/4 in.), 4.7 gpm (1 1/2 in.), 4.7 gpm (2 in.).

NOTE: Cv is equal to capacity at 1 psi pressure drop.

Table 2: MV876B Timer Selections

Planning the Installation

The F76S filter should be sized based on the required flow rate and the resulting pressure drop across the filter. For most applications, it is recommended to size the F76S to avoid pressure drops exceeding 3 psi.

Example: To determine the required F76S size for a flow rate of 30 gpm, consult Table 1. At 3 psi pressure drop, a 1-inch filter can provide 31 gpm without exceeding the 3 psi pressure drop limit.

Increased pressure drop occurs when higher velocities are maintained to increase capacity within a given filter size. Severe pressure drops can be encountered as capacity approaches that of the pipe size. To ensure proper backwash cycle operation and effective cleaning, follow all recommendations in Figure 2. Figure 2a illustrates an ideal installation.

Note: Filter installations vary. Always consider the size, type, and amount of dirt/debris, and the flow rate when selecting a screen and deciding whether to install multiple F76 filters in parallel.

Installation Recommendations (Figure 2)

• Figure 2a (Ideal Installation): A funnel mounted directly under the backwash port is the best installation layout.
• Figure 2a (Inlet Pipe): Ensure the inlet pipe is not downsized. Do not use 1/4 or 3/8 inch tubing on 1/2 or 3/4 inch models.
• Figure 2c (Backwash Outlet): Ensure the backwash outlet pipe is not downsized, long, or crimped. Install a short, oversized pipe on the backwash outlet. Avoid using a low-capacity solenoid valve for automatic backwash.
• Figure 2d (Backwash Outlet Height): Ensure the backwash outlet is not raised above the F76S. If it must be raised, increase inlet pressure by 5 psi for every 10 feet of elevation increase.
• Figure 2e (Pump Sizing): Ensure the F76S is not used with an undersized pump, as this may result in inadequate pressure or flow.
• Figure 2f (Bypass Installation): Ensure the F76S is not installed in a bypass configuration across a pump.

Commercial and Industrial Installations (1-1/2 and 2 in. models)

Commercial and industrial applications often have high flow requirements. For optimal operation, limit the flow across the F76S screen. For instance, a 2-inch pipe might handle a 120 gpm flow at 12 fps linear velocity across a clean screen. High linear velocities can force dirt deep into the screen, making it difficult to backwash and leading to premature plugging. In such cases, installing multiple F76 filters in parallel (as shown in Figure 3) is recommended.

Advantages of Parallel Installation:

• Increased cleaning capacity, reducing backwash intervals.
• Eliminates system downtime by allowing one F76S to be backwashed while others maintain required flow.

For high-flow commercial and industrial applications, screens require regular cleaning. An MV876 Automatic-Backwash Control can be installed to automate the backwash process for the F76S.

F76S Installation

1. Shut off the water supply by closing the main water supply valve.
2. Install the F76S in the water line, ensuring the arrow on the unit points in the direction of water flow.
3. Install a pressure gauge in the F76S center port (refer to Figure 5).
4. Ensure the F76S air vent is open.
5. Slowly open the water supply valve.
6. Once the F76S sump fills with water, close the air vent and fully open the water supply valve.

Important: If using an MV876, stop here and install the MV876.

MV876 Installation on an F76S

When adding an MV876 to an F76S, follow these steps:

1. Open the backwash outlet ball valve.
2. Remove the backwash outlet handle.
3. Install the MV876 unit. Refer to Figures 5 and 6.
4. Note: Rotating the MV876 closes the backwash outlet ball valve.
5. Ensure the F76S air vent is open.
6. Slowly open the water supply valve.
7. Once the F76S sump fills with water, close the air vent and fully open the water supply valve.
8. Program the desired backwash interval by pressing the program button until the correct interval number appears on the display.

Setting Pressure Gauge Needles

The black needle on the pressure gauge indicates the F76S outlet pressure. With clean screens and at maximum recommended flow, there is a small pressure drop (approximately 3 psi) across the F76S.

The red needle is a stationary indicator used to monitor the backwash interval.

Note: This procedure assumes a constant inlet pressure. If inlet pressure varies, an additional gauge on the inlet piping or monitoring the air vent can provide more information about actual pressure differentials.

1. Perform a backwash cycle on the F76S to ensure the screens are clean.
2. With the F76S operating, rotate the clear gauge cover to align the red needle with the black needle.

As the F76S operates and screens become plugged, the outlet pressure (black needle) will drop. Backwash the F76S when the black needle reads approximately 5 psi lower than the red needle. However, backwash intervals can vary based on installation conditions.

For residential applications, a guideline is to backwash the F76S weekly, regardless of need, to maintain peak operating efficiency.

Fitting Batteries and Fuses for MV876

Batteries (not included) provide power to the MV876 during power outages, which is crucial if a power loss occurs during the reverse rinsing cycle. The MV876 requires four AA alkaline batteries. Install these batteries in the MV876 cover.

Caution: Electrical Shock or Equipment Damage Hazard. Disconnect power supply before installation to avoid shocks or short circuits.

1. Unscrew the four housing screws and set them aside (see Figure 8).
2. Remove the MV876 cover (see Figure 8).
3. Insert four AA alkaline batteries (see Figure 9).
4. Replace the cover.
5. Replace and tighten the four housing screws.
6. Reconnect the power supply.

Notes:

• To prevent unnecessary battery drainage, connect the MV876 to power as soon as possible after inserting new batteries.
• Replace batteries after a power loss to ensure battery power availability.

Replacing the MV876 Fuse:

If the 800 mA fuse blows, replace it:

Caution: Electrical Shock or Equipment Damage Hazard. Disconnect power supply before installation.

1. Unscrew the four housing screws and set them aside (see Figure 8).
2. Remove the MV876 cover (see Figure 8).
3. Remove and discard the old fuse (see Figure 10).
4. Insert a new 800 mA fuse (see Figure 10).
5. Replace the cover.

Wiring

Caution: Electrical Shock or Equipment Damage Hazard. Disconnect power supply before installation.

Important: All wiring must comply with applicable codes and ordinances.

MV876 Wiring

1. Mount the AT140A1034 Transformer and wire according to Figure 11.
2. Ensure the F76 air vent is open.
3. Slowly open the water supply valve.
4. Once the F76 sump fills with water, close the air vent and fully open the supply valve.
5. Reconnect power to the system. The MV876 will perform one backwash cycle (approximately 20 seconds) upon powering up.
6. Set the MV876 backwash interval to the desired setting (refer to the Operation section).
7. Verify MV876 operation by interrupting and restoring primary power to the transformer. The MV876 should backwash the F76 once upon power restoration.

Operation

The F76S Water Filter removes sediment and debris using an upper and lower screen. During normal operation, water flows through the lower screen, while the upper screen filters it. (See Figure 12a.)

Over time, the lower screen can become obstructed, reducing efficiency and causing a pressure drop across the F76S. Periodic backwashing is necessary.

A suggested backwash interval is either once per week for residential applications or when the black pressure gauge needle reads approximately 5 psi lower than the red needle.

To manually backwash the F76S, open the backwash outlet at the bottom of the F76S. This action forces the entire filter insert downwards. Water flow to the outer side of the lower screen is blocked. The upper filter then removes sediment and debris from the water.

While the upper screen filters water, a portion of this filtered water is directed through the impeller to backwash the lower screen from the inside out. The remaining filtered water continues to supply downstream needs.

Water jets from the rapidly spinning impeller enhance the reversed water flow, effectively removing trapped sediment and debris from the lower filter. This sediment is then drained through the backwash outlet. Cleaning the lower screen takes approximately 20 seconds (See Figure 12b).

With proper backwashing at the correct intervals, the F76S requires no maintenance.

Determining Backwash Interval

Backwash intervals for F76S filters vary depending on:

• The level and type of sediment in the local water supply.
• Water usage patterns.

Example: In regions with seasonal lawn watering, water usage is higher in summer than in winter. Therefore, the F76S may require more frequent backwashing during summer months.

Accurately determining the backwash interval ensures the F76S operates at higher efficiency.

Procedure to determine F76S backwash interval:

1. Perform a system backwash to ensure the lower screen is clean.
2. The black pressure gauge needle indicates outlet pressure. With clean screens, inlet pressure equals outlet pressure due to negligible pressure drop.
3. Rotate the clear gauge cover to set the red needle to match the black needle.
4. Record the date and time.
5. Monitor the F76S closely. Over time, as screens obstruct, outlet pressure will drop.
6. Note: The F76S typically requires backwashing when the black needle is about 5 psi lower than the red needle. Actual intervals may vary.
7. Record the date and time again. Residential applications might require backwashing once every few weeks to once per week. Industrial applications may require backwashing several times a day.
8. Backwash the F76S regularly at the determined interval, either manually or automatically.
• Manual Backwash: Open the backwash outlet for approximately 30 seconds. (Note: The exact time may vary, but 30 seconds is a standard guideline for cleaning the lower screen.)
• Automatic Backwash: Install an MV876 Automatic-Backwash Valve and select the appropriate backwash interval.

F76S Replacement Parts List

Parts and accessories are available for new style F76S filters.

Figure 13: F76S Exploded View: This diagram shows the various components of the F76S filter, with parts labeled A through S, corresponding to the replacement parts list above. It illustrates how the different parts, including the pressure gauge (A), tailpieces (B), union nuts (C), gaskets (D), guide barrel (E), screen inserts (F, G, J), base spring (H), chamber O-ring (J), sump kits (K), ball valve components (L, M, N, P, Q, R), and drain connector (S), assemble to form the complete unit.

Diagram Descriptions

Figure 1: F76S Dimensions: This figure displays a diagram of the F76S filter with dimensions labeled L (Length), D (Diameter), H (Height), and h (Height from base to top of valve). It also shows an integrated pressure gauge.

Figure 2: Installation Recommendations:

• Figure 2a (Ideal Installation): Depicts an F76S filter with a funnel positioned directly beneath the backwash port, indicating optimal installation for managing backwash discharge.
• Figure 2a (Inlet Pipe): Ensure the inlet pipe is not downsized. Do not use 1/4 or 3/8 inch tubing on 1/2 or 3/4 inch models.
• Figure 2c (Backwash Outlet): Ensure the backwash outlet pipe is not downsized, long, or crimped. Install a short, oversized pipe on the backwash outlet. Avoid using a low-capacity solenoid valve for automatic backwash.
• Figure 2d (Backwash Outlet Height): Ensure the backwash outlet is not raised above the F76S. If it must be raised, increase inlet pressure by 5 psi for every 10 feet of elevation increase.
• Figure 2e (Pump Sizing): A diagram showing an F76S filter connected to a pump, warning against using an undersized pump that might not provide adequate pressure or flow.
• Figure 2f (Bypass Installation): A diagram showing an F76S filter installed in a bypass configuration across a pump, indicating this is an incorrect installation method.

Figure 3: Parallel Installation of Three F76S Water Filters: This diagram shows three F76S water filters plumbed in parallel, a configuration recommended for commercial and industrial applications with high flow requirements.

Figure 4: Installing the F76S: This diagram shows the F76S filter being installed into a water line, with an arrow indicating the direction of water flow. It also shows an isolation valve and a pressure gauge port.

Figure 5: Installing the F76S: A close-up view of the F76S filter installation, highlighting the placement of the pressure gauge.

Figure 6: Installing the MV876: This diagram illustrates the MV876 automatic-backwash control unit being attached to the F76S filter.

Figure 7: Final Position of MV876 and F76S Components: Shows the assembled F76S filter with the MV876 unit connected.

Figure 8: Removing the MV876 Cover: Illustrates the process of removing the MV876 cover by unscrewing four housing screws.

Figure 9: Installing Batteries in the MV876: Shows the correct placement of four AA alkaline batteries within the MV876 unit.

Figure 10: Replacing the MV876 Fuse: Depicts the process of replacing a blown fuse in the MV876 unit.

Figure 11: Wiring Diagram for F76 with MV876: This diagram shows the electrical connections required for the MV876, including the transformer (AT140A1034) and power supply.

Figure 12: Water Flow Through the F76S:

• Figure 12a (F76S During Normal Flow): Shows an enlarged cross-section of the F76S filter, illustrating the path of water flow during normal operation, highlighting the screen and backwash impeller.
• Figure 12b (F76S During Backwash Cycle): Shows an enlarged cross-section of the F76S filter during a backwash cycle, illustrating the reversed water flow that removes debris and sediment from the lower screen.

Figure 13: F76S Exploded View: This diagram displays all the individual components of the F76S filter, with each part labeled with a letter (A-S) corresponding to the replacement parts list, showing how they fit together.