Introduction

Eureka Byepass Rotameters are ISO 9001:2008 certified flow measurement devices used in various industrial applications. They are designed for pipe sizes 1 inch and above and are suitable for clean, non-viscous liquids and various gases. Special models are available for corrosive fluids. These rotameters can be installed in both horizontal and vertical piping systems.

Working Principle

The Byepass Rotameter operates on the differential pressure measurement principle and consists of three main components:

• Main Line Orifice Plate: Installed in the main pipeline, it creates a differential pressure proportional to the flow rate by restricting flow.
• Indicating Rotameter: A glass or metal tube rotameter installed in a bypass line with a range orifice that replicates the differential pressure created by the main orifice plate, functioning as a differential pressure measuring device.
• Bypass Piping: Diverts a small portion of the main flow through the rotameter. It includes isolation valves for maintenance.

Types of Pressure Tappings

Eureka offers three designs based on pressure tapping methods:

1. Corner Tapping (Carrier Ring Type - BPC Series): Pressure taps drilled through a carrier ring assembly, opening at the orifice plate corners. Suitable for pipe sizes 25 mm to 450 mm NB. The carrier ring is sandwiched between line flanges and can be one or two-piece.
2. Flange Tapping (BPF Series): Pressure taps drilled on orifice flanges welded to the main pipe, located 24.5 mm from the orifice plate. Available for pipe sizes 50 mm to 900 mm NB, typically with weld neck flanges. Supply includes orifice plate, flanges, rotameter, and optional bypass arrangement.
3. D & D/2 Tapping: Pressure taps drilled directly on the main pipe at distances of D (pipe internal diameter) upstream and D/2 downstream from the orifice plate. Available for pipe sizes 50 mm to 1000 mm NB. Supply includes orifice plate and rotameter; mainline flanges and bypass piping are customer-supplied.

General Construction

The bypass rotameter assembly includes components such as float, measuring tube (glass or metal), scale, float retainer, end blocks, range orifice, isolating valves, gland packings, carrier rings (single or two-piece), bypass line, and orifice plate.

Materials of Construction

• Orifice Plate: 316 Stainless Steel, Ebonite, Hastelloy (for flange tappings only)
• Carrier Rings: 316 Stainless Steel, Mild Steel, Carbon Steel
• Orifice Flanges: ASTM A-182 / A-105, standard ASME B16.36
• Pipeline: 316 Stainless Steel, Mild Steel, Carbon Steel
• Rotameter Wetted Parts: 316 Stainless Steel, Mild Steel, Carbon Steel, Rubber Lined Steel, PTFE Lined Steel (for D & D/2 tappings)
• Accessories: High and low flow alarms, transmitters (on request)

Performance Specifications

• Accuracy: ±2% of full flow
• Rangeability: 7:1 (standard), up to 10:1 on request

Standard Flow Ranges for Water at 20°C

Data Required for Sizing

• Name of fluid
• Specific gravity at operating temperature
• Viscosity at operating temperature
• Operating temperature and pressure
• Measuring range
• Desired material of construction

Model Number Identification

The model number is constructed using codes for type, tapping, material, line size, tube size, accessories, and flow direction. For example:

BP D SS 250 3

• BP: Byepass Rotameter
• Tapping Type: C (Corner), D (D & D/2), F (Flange)
• Material: SS (Stainless Steel), MS (Mild Steel), TL (PTFE Lined), RL (Rubber Lined), CI (Cast Iron)
• Line Size: e.g., 25, 50, 250 NB
• Tube Size: MTS-1, PG-2 (low pressure), PG-3 (normal pressure), PG-4 (corrosive)
• Accessories: FSPL (single flow switch), FSPHL (double flow switch), T (transmitter), WE (weatherproof)
• Flow Direction: Horizontal (left to right), VU (vertical up), VD (vertical down)

Installation and Maintenance

Typical installation drawings show configurations for horizontal and vertical pipelines with carrier rings, socket weld flanges, and weld neck flanges. Isolation valves are included in the bypass piping for maintenance. Straight pipe lengths upstream and downstream of the orifice plate must be maintained as per specified tables to ensure accurate measurement.

Remarks and Limitations

• Rubber lined, cast iron, and PTFE lined materials are not available for corner and flange tapping types.
• Corner tapping is applicable up to 450 NB size only.
• Flow switches are provided only for tube size PG-3.
• Weatherproofing is not applicable with flow switch accessories.

Summary

Eureka Byepass Rotameters provide reliable flow rate indication through differential pressure measurement using an orifice plate and a bypass rotameter. Multiple tapping types and materials allow customization for various industrial fluids and conditions. The product offers good accuracy and rangeability, with options for alarms and transmitters. Proper installation and maintenance are critical for optimal performance.