Tel: 
Email: 
WhatsApp: Description
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Model | Foxboro E69F-BI2-MRS |
| Product Type | Field-Mounted I/P Current-to-Pneumatic Converter |
| Input Signal | 4–20 mA DC, loop-powered (no separate power supply required) |
| Input Impedance | 170 Ω (for 4–20 mA range) |
| Output Signal | 3–15 psi (20–100 kPa) pneumatic |
| Accuracy | ±1.0% of span (for 3–15 psi output range) |
| Linearity | ±0.5% of span, typical |
| Hysteresis | ±0.5% of span, typical |
| Repeatability | ±0.25% of span, typical |
| Supply Air Pressure | 19–23 psi (130–160 kPa) clean, dry instrument air |
| Air Consumption | ~0.5 scfh (rated conditions, 3–15 psi output) |
| Enclosure | Die-cast aluminum, weatherproof, IP65 / NEMA 4 |
| Pneumatic Connections | 1/4 NPT (air supply and output) |
| Electrical Connection | 1/2-inch conduit |
| Operating Temperature | -30 °C to +60 °C (normal); -40 °C to +80 °C (limits) |
| Mounting | Surface, valve yoke, or 2-inch vertical pipe |
| Action | Direct or reverse (specified at order) |
Product Introduction
The E69F series is one of those workhorse instruments that shows up in nearly every older Foxboro DCS valve loop. It sits between the control system and the pneumatic actuator, turning a 4–20 mA command into a clean, proportional air pressure signal. The BI2 configuration is the most common variant — 4–20 mA in, 3–15 psi out, direct action.What makes the -MRS configuration practical in the field is the built-in filter regulator and dual gauges. The filter regulator cleans up the instrument air supply and sets the correct supply pressure, while the two gauges let you see supply pressure and output pressure at a glance during commissioning or troubleshooting. No extra manifold, no separate regulator block, no guessing. I have seen technicians save hours during a turnaround simply because they could read both pressures without hunting for test points.The galvanometer-style torque motor design is inherently resistant to vibration and atmospheric contamination. Unlike some voice-coil I/Ps, the E69F has enough clearance between the coil and housing that dust and corrosion do not immediately jam the mechanism. That is why these units still turn up in refineries, power plants, and chemical facilities after decades of service.
Quality SOP & Tech Pitfalls
The Lab Report (SOP):
- Visual inspection — verify nameplate reads E69F-BI2-MRS, check enclosure integrity, gauge condition, and filter regulator assembly.
- Mechanical check — confirm 1/4 NPT ports are clean and undamaged, conduit entry is intact, and mounting hardware is present.
- Bench test — apply 4 mA and 20 mA from a loop calibrator; verify output pressure reads 3 psi and 15 psi respectively.
- Linearity check — step through 4, 8, 12, 16, 20 mA and record output pressures; verify within ±1.0% of span.
- Hysteresis check — approach each test point from both increasing and decreasing current directions.
- Filter regulator function — verify supply pressure regulation and absence of air leaks.
- ESD-safe packaging with port plugs and gauge protection before shipment.
The Engineer’s Warning (Pitfalls):
Three common failures I see in the field. First, dirty instrument air kills I/Ps faster than anything else. The built-in filter regulator helps, but it is not a substitute for a clean air header. If your supply air is wet or oily, the nozzle-flapper mechanism will clog and the output will drift or stick.Second, technicians confuse the E69F with a positioner. It is not. The E69F is an I/P converter. It takes a current signal and produces air pressure. It does not sense valve position, does not close a position loop, and does not compensate for actuator friction. If your valve is hunting or has poor positioning accuracy, the problem may be the actuator or the positioner — not the I/P.Third, the suffix code matters. E69F-BI2, E69F-BI2-S, E69F-BI2-MS, and E69F-T12-JRS are not identical. The -S suffix on BI2-S means explosion-proof junction box, not gauges. The -MS means marine/corrosion-resistant coating. The -JRS on a T12 model means explosion-proof housing with regulator and gauges. Order the wrong suffix and you may end up with an enclosure that does not match your area classification or missing the gauges you expected.
Installation & Configuration Guide
- Pre-Installation (⚠️ Critical): Isolate the pneumatic supply and verify the loop is in a safe state. Confirm the replacement nameplate matches the original: E69F-BI2-MRS, correct input/output range, and correct action (direct or reverse).
- Removal: Label the electrical conduit and pneumatic tubing. Disconnect the 1/2-inch conduit fitting and the 1/4 NPT air lines. Remove the mounting bolts. Note the mounting orientation — the E69F is calibrated for vertical mounting unless otherwise specified.
- Installation: Mount the new unit in the same orientation. Connect the instrument air supply to the supply port and the output port to the actuator/positioner. Connect the electrical conduit. Ensure all fittings are tight and leak-free.
- Commissioning: Apply instrument air (19–23 psi). Apply 4 mA and verify 3 psi output. Apply 20 mA and verify 15 psi output. Adjust zero and span trim pots if needed. Verify both gauges are reading correctly. Check for air leaks. Document the installation.
Compatible Replacement Models
| Model | Compatibility | Notes |
|---|---|---|
| Foxboro E69F-BI2-MRS (same) | ✅ Drop-in | Best option. Match nameplate exactly. |
| Foxboro E69F-BI2 | ⚠️ Conditional | Same core I/P function, but may lack the -M (junction box), -R (regulator), or -S (gauges) options. Verify mechanical and pneumatic fit. |
| Foxboro E69F-BI2-S | ⚠️ Conditional | Explosion-proof junction box variant. Different electrical enclosure. Not a direct swap in non-hazardous areas without conduit review. |
| Foxboro E69F-T12-JRS | ⚠️ Conditional | Explosion-proof housing with regulator and gauges. Different enclosure type (-T vs -B). Requires area classification review. |
| Schneider Electric IP26 series | ⚠️ Project-level | Official successor family to the E69F. Requires mechanical and pneumatic interface review. |
| Generic 4–20 mA to 3–15 psi I/P | ⚠️ Project-level | Functionally equivalent I/P conversion, but mounting, port sizes, and certification may differ. Requires loop validation. |
Frequently Asked Questions (FAQ)
Q1: What does the “MRS” suffix mean?
M = miniature junction box with 1/2 NPT conduit (front entry); R = adjustable filter regulator; S = supply and output pressure gauges.Q2: Does the E69F-BI2-MRS need a separate power supply?
No. It is loop-powered by the 4–20 mA signal itself. The host system (DCS/PLC) provides the loop voltage.Q3: Can I use it in a hazardous area?
The -B enclosure is weatherproof, not explosion-proof. For hazardous areas, you need the -T (threaded-cover explosion-proof) housing variant, such as E69F-TI2-J. Verify the nameplate and your area classification.Q4: What is the difference between an I/P converter and a valve positioner?
An I/P converter (like the E69F) converts current to air pressure. A valve positioner senses the actual valve position and adjusts air pressure to match the command signal. They are different devices. The E69F can feed a positioner or directly drive a simple pneumatic actuator.Q5: Why is my E69F output drifting?
Most commonly: dirty or wet instrument air, a clogged nozzle/flapper, or a failing filter regulator element. Check the air supply quality first. Then check for leaks. Then verify zero and span calibration.Q6: What is the Schneider Electric replacement?
The IP26 series (e.g., IP26-1000) is the current successor to the E69F family. However, mechanical mounting, pneumatic connections, and electrical interfaces may differ, so a like-for-like swap requires verification.Q7: Can I mount it horizontally?
The E69F is calibrated for vertical mounting. Tilting more than 5 degrees from vertical can cause up to 0.25% of span zero shift. If horizontal mounting is unavoidable, recalibrate in the installed position.
