Foxboro E69F Converter



Foxboro E69F Converter

Foxboro E69F on-site installed current pneumatic signal converter is used to convert standard DC input signals into proportional pneumatic outputs for driving other pneumatic instruments or control valves. It has a small size and flexible installation, and can be fixed on surfaces, valve yokes, or DN50/2-inch vertical pipes. When replacing or troubleshooting on site, one should not only focus on the "4-20mA input, 3-15psi output" line, but also check the housing type, input range, output range, positive and negative effects, split range settings, electrical safety classification, and optional components together. Otherwise, it is easy to encounter problems such as "new parts installed but not functioning, output reverse, and not suitable for explosion-proof areas".

Confirm the model and function first, then discuss replacement

The E69F model number consists of a housing, input, output, and optional components. The shell "- B" is a bolted cover, weatherproof type, used for all non explosion proof applications; The "- T" is a threaded cover and explosion-proof type, which must be selected for all explosion-proof applications. Input "I" as 4-20mA, 4-12mA, or 12-20mA split range, with an impedance of 170 Ω; The 'H' has a split range of 10-50mA, 10-30mA, or 30-50mA, with an impedance of 27 Ω. Output code 2 is 20-100kPa, 3-15psi, 0.2-1.0bar; Code 3 is 40-200kPa, 6-30psi, 0.4-2.0bar or 3-27psi; Code 7 is 7-125kPa, 1-18psi, 0.07-1.3bar; Code 8 is 7-220kPa, 1-32psi, 0.07-2.2bar. When used for executing mechanisms, code 7 or code 8 are more common. The positive effect is an increase in input and an increase in output; The reaction is an increase in input and a decrease in output, and replacement must be consistent with the direction of valve failure safety.

The optional components also affect the replacement: - J is the overall explosion-proof junction box, - M is the 1/2NPT before the micro junction box, - P is the 1/2NPT after the micro junction box, - R is the adjustable filter pressure regulator without a gauge, and - S is the supply/output pressure gauge. Note that - M and - P cannot be used for - T casing; PG11 horn type cable connection cannot be used for electrical classification of CS-E/CD-A and CS-E/FD-A. If the original equipment comes with customer labels, special junction boxes, or split range inputs, the data card and AS code should be recorded before replacement to avoid new parts being unable to be wired or having incorrect addresses.

The installation location and gas source are the primary sources of zero drift

The E69F adopts an ammeter type motor, with a large gap between the coil and the housing. Corrosion and dust caused by normal atmospheric changes are not easily trapped in the mechanism, making it more resistant to dirt than voice coil instruments. But it is still sensitive to installation posture: it is calibrated for vertical installation at the factory, and if installed horizontally or obliquely on site, a maximum 5-degree angle change can cause a zero offset of 0.25% of the range. The safest approach is to calibrate the zero position at the actual installation location, rather than adjusting it on the experimental bench and then installing it. The installation surface should be able to withstand weight, with E69F weighing approximately 2.3kg (5lb). When fixing it on the valve yoke or pipeline, extra stress should be avoided.

The quality of the gas source directly affects the stability of the output. The supply pressure must be at least 20kPa (3psi, 0.2bar) higher than the maximum output signal pressure, and the air should be free of oil, dust, and water, in accordance with IEC 654-2. When the nominal supply pressure is 140kPa/20psi/1.4bar, the working range is 130 to 160kPa; When the nominal pressure is 240kPa/35psi/2.4bar, the working range is 225 to 260kPa. Output code 2 consumes approximately 0.50m ³/h (0.30scfm) of gas; At a supply pressure of 140kPa, codes 3, 7, and 8 have a flow rate of approximately 1.3m ³/h (0.75scfm), and at a supply pressure of 240kPa, they have a flow rate of approximately 1.7m ³/h (1.0scfm). If the on-site gas source contains oil and water, it is recommended to install a filter pressure reducer; -The R option is an adjustable filter pressure regulator without a gauge. When monitoring the supply pressure and output, select the - S pressure gauge. The air port is 1/4NPT, the electrical port is a 1/2-inch conduit connector, and the internal leads are 0.5m, 1.00mm ² (18AWG) twisted pair.

Zero position, range, and performance troubleshooting

Zero position adjustment can be done externally using a screwdriver; Adjust the range to internal wrench adjustment. On site, if there is a situation where the output is not 3psi when inputting 4mA, check the zero position first. If there is a situation where the output is less than 15psi when inputting 20mA, check the range and supply pressure first. The zero drift caused by changes in supply pressure is less than 0.04% of the range/kPa (0.25%/psi). If the supply pressure fluctuates greatly, the output will drift accordingly. The ambient temperature varies by 28 ℃ (50 ° F) within the working range of 0 to 60 ℃, with zero and range offsets not exceeding ± 1.0% of the range; The environmental limit is -40 to+80 ℃, and the humidity is 0 to 100% without condensation. Tilt at 5 degrees with a maximum zero drift of 0.25% range, which can be eliminated by calibration at the actual position. When the impact is 300m/s ² (30g), the maximum zero drift range is 0.5%. The vibration and impact effects are suppressed by rigid feedback flexible parts and low-quality components, but the converter should still be avoided from being installed on pipelines with strong vibration on site.

In terms of performance indicators, the accuracy of output codes 2 and 3 is ± 1.0% range, and codes 7 and 8 are ± 2% range; Linear typical ± 0.5%, repeatability typical ± 0.25%, hysteresis typical ± 0.5%, dead zone 0.1% range. If the on-site performance shows "output jitter and poor repeatability", first check whether the gas source contains water, whether the nozzle baffle is contaminated, whether the output pipeline is leaking, and then check the coil and feedback components. If it is manifested as "linear difference but adjustable zero range", check whether the valve or actuator load exceeds the converter capacity, whether the output pipeline is too long, and whether the joint is leaking air.

Common Fault Tree

No output or no change in output. First, confirm that the input circuit has 4-20mA or 10-50mA and impedance matching (170 Ω or 27 Ω); Confirm again that the supply pressure has reached the nominal value and is higher than the maximum output of 20kPa; Check if the positive and negative effects are selected incorrectly. If there is input, voltage supply, and output, check the polarity of the electrical wiring, open/short circuit of the coil, and blockage of the air circuit. Explosion proof type - T must be equipped with - J junction box or compliant cable sealing. PG11 ordinary gland cannot be used in situations that require flame isolation.

Output in reverse. Positive and negative effects are chosen to be opposite. If the original valve is "fault closed" during replacement, the new converter may react and cause the valve opening to be reversed. Therefore, the valve must be reselected according to its function and cannot be forcibly changed by adjusting the zero position.

Zero drift. First check the installation tilt and calibration position, then check for supply pressure fluctuations, ambient temperature, and water content in the gas source. The impact of supply pressure may be small, but long-term fluctuations will be superimposed. If the zero position cannot be adjusted, check whether the feedback flexible component is deformed and whether the coil is stuck.

Insufficient output or inability to carry load. Verify the output code and supply voltage. Code 2 has a smaller capacity, code 3/8 is larger, and code 7 is centered. When the supply pressure is lower than the maximum output+20kPa, the output will be "blocked". Air leakage, filter blockage, and inaccurate output meter can also cause misjudgment.

Abnormal increase in gas consumption. Check for leaks in the output pipeline and joints, gaps between nozzle baffles, and water accumulation in the filter pressure reducer. Sudden increase in gas consumption is often not an electrical issue, but rather contamination of the gas path seal or baffle.

Explosion proof area replacement failed. Let's first look at the classification of electrical safety. FM explosion-proof is suitable for Class I Groups C, D Division 1, Class II Groups E, F, G Division 1, temperature Class T6, only E69F-T, classification CS-E/FD-A; FM non ignition is suitable for Class I Groups A, B, C, D Division 2, Class II Group G Division 2, - B, and - T, CS-E/FN-A。 CSA certification for Class I Groups A, B, C, D Division 2- B/- T, CS-E/CN-A; CSA Explosion proof Class I Group D, Class II E, F, G, Class III Division 1- T, CS-E/CD-A. ATEX flame explosion-proof EEx d IIB Zone 1, Ta -40 to+80 ℃, T5 uses - T, CS-E/LD-E, and requires - J overall explosion-proof junction box. For intrinsic safety applications, it is necessary to verify the associated equipment: FM intrinsic safety certification module or Honeywell Class 38 Barrier 38454-0000-0110-113-F5B5, etc., CSA 170/27 Ω coil connected to CSA certified Invensys I/O module, ATEX intrinsic safety EEx ia IIC Zone1/Zone1/- B/- T, CS-E/KA-E; ATEX non ignited EEx nA IIC Zone 2 uses - B/- T, CS-E/KN-A. If the electrical classification code changes during replacement, even if the mechanical interface is the same, it cannot be directly replaced.

Junction boxes, labels, and maintenance details

The shell is made of die cast low copper aluminum alloy body and cover, coated with epoxy powder, meeting IEC IP65 and NEMA Type 4 standards. The data card can accommodate up to 86 characters and spaces for customer tags; If not enough, stainless steel customer labels can be added, with a maximum of 10 lines and 40 characters per line, and an AS code MTS. Micro junction box approximately 64 × 58 × 33mm, IP65/NEMA 4, available in 1/2NPT, M20, PG11 or PG13.5, front/rear wiring, non explosion proof application; 1/2NPT forward is selected as - M, backward is selected as - P, and other connections follow the AS code from MB-A to MB-F. Explosion proof applications should choose - J integral explosion-proof junction box, PG11 horn type connection should be matched with - J, and cannot be used for CS-E/CD-A and CS-E/FD-A. In terms of size, the explosion-proof type has a diameter of about 150mm, allowing 102mm of cover removal space, with a total length of about 290mm; a clearance of 150mm is required for zero adjustment; Gas output 1/4NPT, electrical input 1/2-inch conduit. The weight is 2.3kg, and the installation bracket and pipeline fixation should be able to withstand the tension of cables and air pipes.

During maintenance, it is recommended to record the model number, input range, positive and negative effects, output code, electrical classification, range setting, optional components, actual installation position, supply voltage value, and zero/range calibration value. Check the air source filter and output meter every six months, and verify the zero position at the actual installation location every year; Before replacing the FBM or valve, confirm the direction of action of the converter to avoid process fluctuations caused by "reverse valve opening". When replacing a discontinued old converter, don't just look at its appearance and interface. First, compare the six items of "shell - B/- T, input I/H, output 2/3/7/8, positive and negative effects, electrical classification, options J/M/P/R/S" one by one, then check the supply pressure, air consumption, and output capacity, and finally calibrate at the actual installation position. This can not only avoid misuse in explosion-proof areas, but also reduce common problems such as zero drift, insufficient output, and reverse action.