Optimal installation will allow a straight run of pipe for 10 diameters upstream and 5 diameters downstream but the switch can be successfully installed in less than optimal conditions. The additional turbulence can be compensated for by careful selection of the return spring and/or perhaps a shorter paddle length. Please let us know if these conditions exist at the quoting stage.
Optimal installation is vertical (within 5°) on a horizontal pipe run. However, the switch can be mounted in any position rotational on the axis of the pipe*. If vertical piping – adjust for gravity with spring tension (B). Please let us know at the quoting stage if you do not plan to install the switch vertically in a horizontal run of pipe (as depicted in the graphic to the right). * Keep in mind that mounting in a horizontal position on a vertical pipeline will effect the switch’s activation/deactivation capabilities.
Screwed models are to be installed with a weld-a-let, thread-a-let, or half coupling.
Pressure and Temperature Rating: The pipeline’s operating pressure and temperature must be within the limits shown on the PEECO nameplate to prevent a catastrophic failure of the switch.
Material Compatibility. The wetted parts of the switch, particularly the paddle (the part that extends into the pipe), must be made of materials compatible with petroleum to prevent corrosion and premature failure. The flange and body appear to be metal, likely steel, which is common for this application.
Pipe Size and Flange Standard: The switch’s flange must match the pipeline’s flange in terms of size, pressure class (e.g., 150#, 300#), and bolt pattern (e.g., ASME B16.5).
Isolate the Pipeline. Before any work begins, the section of the pipeline where the switch will be installed must be isolated. This means shutting off the flow, depressurizing the line, and draining the petroleum product from that section. The line must be thoroughly purged and de-gassed to remove all flammable vapors.
Secure and Prepare the Pipe. The pipeline section should be supported to ensure it remains stable. For flange mounted flow switches, the flanges on the pipe must be clean and free of rust, scale, or petroleum residue. A new, compatible gasket must be placed between the switch’s flange and the pipeline’s flange.
Prepare the Vane. Tee & wafer models install directly in the pipe run. Do not alter paddle. For insertion style flow switches, cut paddle length to within approximately 1/2” clearance from the bottom of the pipe. Contour corners as necessary to insure no contact with pipe. The flexible paddle should always be within the run of pipe. If a riser is present, the 3/8” round stem should run the length of the riser before the point of paddle attachment.
Install the Switch.Mount switch with conduit connection downstream (pointing in the direction of flow). The flow switch is a “paddle-style” or “insertion-style” unit. The paddle extends into the flow path. It’s crucial to orient the switch correctly so the paddle operates freely and is not obstructed by the pipe wall or other components. Align the switch flange with the pipeline’s flange, ensuring the bolt holes match perfectly. Insert all the bolts through the flanges and hand-tighten them. Using a torque wrench, tighten the bolts in a crisscross or star pattern. This ensures even pressure on the gasket, which is essential for a leak-proof seal. It prevents warping the flanges and damaging the gasket.
Connect Electrical and Re-commission. The switch is a mechanical-to-electrical device. A qualified electrician must make the electrical connections inside the explosion-proof housing, following the wiring diagram. The system must be pressure tested and leak-checked before reintroducing the petroleum product
Base travel for the N Series & E Series is a 1/4″. Based travel for H Series is 1/16″.
All PEECO switches require field setting unless calibration has been requested and provided. Switch adjustment should be made in the middle of the physical range of movement.
Adjustment (field setting) procedure:
Disconnect current.
Remove switch cover.
Screw actuating rod (A) in or out to point at which micro switch clicks.
Increase or decrease tension on return spring as necessary to overcome spring balance.
All turns should be done carefully and in small steps.
Screw cover on tightly before re-connection of current.
Return springs (B) may be changed as needed for greater or lesser tension (higher or lower flows). Springs are color coded only as to varying weight or tension – not as to quantitative flow range.
The flow switch is fitted with a color coded spring. The lower the flow trip point, the softer the spring should be.
Installing a PEECO Flow Switch
The microswitch is a type of snap-action switch that works on a simple but precise mechanical principle to control an electrical circuit.
Here’s how it works:
Core Mechanism
The switch contains an internal spring mechanism that is designed to change its contact position very rapidly. It has three terminals:
Common (C): This is the terminal that always has a connection.
Normally Closed (NC): The common terminal is connected to this terminal when the switch is in its resting state (not actuated).
Normally Open (NO): The common terminal is not connected to this terminal in the resting state.
Operation
The switch is activated by a small amount of physical force applied to its overtravel plunger actuator.
Resting State: The plunger is not being pushed. The internal spring holds the contacts in a position where the Common terminal is connected to the Normally Closed terminal. No current flows to the Normally Open terminal.
Actuation: As a force is applied to the plunger, it moves inward. At a very specific and repeatable point, the internal spring mechanism “snaps” over, rapidly changing the contact position.
Actuated State: The plunger is pushed to the actuation point. The Common terminal is now disconnected from the Normally Closed terminal and is connected to the Normally Open terminal. Current can now flow through the circuit connected to the NO terminal.
Release: When the force is removed, the plunger returns to its original position. The spring mechanism “snaps” back, returning the Common terminal to its original connection with the Normally Closed terminal.
The “snap-action” design is crucial because it ensures a very fast transfer of contacts, regardless of how slowly the plunger is moved. This quick break and make action minimizes arcing and extends the life of the contacts. The “overtravel plunger” actuator allows the user to push the plunger past the actual switching point without damaging the internal mechanism, which is useful in many applications.
There are seven springs available: 1. Brown (Softest) 2. Red 3. Orange 4. Yellow 5. Green 6. Blue 7. Purple (Stiffest)
In the absence of any flow data from the customer, PEECO fits the red spring as a standard. (If the switch has too soft a spring, there is a possibility that a high flow trip point cannot be achieved. In addition, the switch can bounce on and off due to the turbulence created around the paddle at higher flow conditions).
To get a lower trip point, the red spring should be swapped out for the brown spring. Once this is done, the trip point screw should be adjusted so that the micro-switch just activates under a no-flow condition.
If the flow switch will still not activate with the low flow, a wider paddle (1-7/8″) can be provided to increase the force produced on the switch at the lower flowrate. If you change to the wider paddle, you may have to adjust the trip point screw to offset for the additional weight of the larger paddle. The downside of doing this is that more pressure drop and turbulence is created at higher flow rates, which may lead to the bouncing effect described above.
PEECO Spring Kit
Relieve Pressure Prior to Disassembling Switch Components.
Switches Equipped with a Dashpot
Time delay of the pot can be adjusted by screwing in (shortening time) or out (lengthening time) the small orifice plug at rear of cylinder. Do not tamper with any other part of the dashpot.
Click To Enlarge
IMPORTANT – BEFORE CONNECTING CURRENT, COVER MUST BE TIGHTLY CLOSED.
