RD312

RD312 Metal Cover Locator: Technical Guide

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Product Overview

The RD312 is a precision metal cover locator. It reduces the time wasted searching for lost or buried valve box covers, vault covers, fuel tanks, reinforced rods (rebar) and manhole covers. With an automatic sensitivity function that adapts to the local environment, the RD312 can be used near metal fences or under parked vehicles without loss of accuracy. 

Its rugged construction of high‑impact ABS plastic and a 22 mm aluminum stem is weatherproof to NEMA 3R and IP54, and the instrument can withstand a 1 m drop onto concrete. Despite this toughness, it weighs only about 1 kg (2.2 lb) and collapses telescopically for compact storage. Eastcom also offers training, repairs and demonstrations to ensure users get the most from their equipment.

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Key Features and Benefits

• Two‑button operation: A green ON/RESET button turns the unit on and automatically sets the optimum gain; a red OFF button powers the instrument down. The simple interface eliminates complex menus and shortens training time.
  
  
• Automatic sensitivity adjustment: The locator automatically adjusts its sensitivity for peak performance, allowing accurate detection even when operating near metal fences or parked cars.
  
  
• Telescopic design: The RD312’s shaft extends for comfortable use and retracts for storage. Operators can adjust the search‑head angle and height to suit the job.
  
  
• Variable audio tone: A built‑in loudspeaker emits a varying pitch; the highest tone indicates the strongest response over a buried cover. Optional headphones can be used in noisy environments.
  
  
• Waterproof search head: The search head is waterproof and can be used in shallow water, making the instrument suitable for flooded or rainy conditions.
  
  
• Lightweight and durable: At just ~1 kg, the RD312 is easy to carry. The ABS/aluminum construction is weatherproof to NEMA 3R/IP54 and withstands a 1 m drop.
  
  
• Discriminates between targets and trash: Advanced electronics ignore small metallic debris such as coins and cans, and the device is not affected by passing vehicles.
  
  
• Long battery life: A single 6LR61 9 V alkaline battery provides approximately 30 hours of operation at 20 °C. Rechargeable battery options are available.
  
  

Technical Specifications

The RD312’s detection range depends on the size and material of the cover being located. Because the actual range is influenced by soil conditions and nearby metallic objects, exact limits cannot be specified. As a guide, the RD312 can detect common covers to the approximate depths shown below:

• Manhole cover (≈25 in/53 cm diameter) – up to 30 in (76 cm) deep
  
  
• Valve box (≈6 in/15 cm diameter) – up to 16 in (41 cm) deep
  
  
• Plastic valve box with metal plate (≈4 in/10 cm diameter) – up to 8 in (20 cm) deep
  
  

The instrument finds other large ferrous items such as cast‑iron covers, galvanized steel manholes and steel fuel tanks. The variable tone audio signal ensures the operator knows when the head is directly over the target.

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Physical and Electrical Specifications

How the RD312 Works

1. Check battery status: Ensure a fresh 9 V battery is installed. The RD312 includes an audio battery‑OK indication and optional rechargeable battery capability.
   
   
2. Extend the locator: Pull the telescopic shaft to a comfortable length and adjust the search‑head angle to suit the terrain.
   
   
3. Power on and reset: Press the green ON/RESET button to switch on the unit and automatically adjust sensitivity. Wait a few seconds for the auto gain to stabilize.
   
   
4. Sweep the area: Hold the search head a few centimetres above the surface and move it in slow, overlapping sweeps. Listen for the pitch increase in the audio tone – the highest tone indicates the strongest signal.
   
   
5. Pinpoint the cover: When the tone peaks, move the locator in a cross pattern to precisely define the cover’s center. Adjust the gain using the auto reset or manual control if required.
   
   
6. Switch off: After locating the cover, press the red OFF button to preserve battery life.

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Typical Applications

The RD312 is ideal for locating:

1. Valve and service boxes: Utility workers can quickly pinpoint buried or paved‑over valve boxes and service access points.
   
   
2. Manhole covers and vault lids: Municipal crews use the RD312 to find cast‑iron or steel manholes under asphalt, concrete or grass. The instrument’s adjustable search‑head angle allows scanning around obstacles and curbs.
   
   
3. Fuel tanks and rebar: The locator helps contractors identify reinforced steel rods in concrete slabs and detect buried fuel tanks or steel plates.
   
   
4. Roadway maintenance: When road surfaces are overlaid with new asphalt, cover positions are often lost. The RD312 finds them quickly, reducing excavation damage and minimizing traffic disruption.
   
   
5. Snow‑covered or flooded sites: The waterproof search head and adjustable telescopic handle make the RD312 usable in shallow water or snow.
   
   

Maintenance and Best Practices

• Battery care: Replace the battery when the audio tone weakens. Use alkaline 6LR61 cells or approved rechargeable packs.
  
  
• Cleaning: Wipe the search head and housing with a damp cloth after use. Avoid solvent cleaners that may damage the plastic housing. Check that the speaker grille is free of debris.
  
  
• Storage: Retract the telescopic stem and store the unit in its padded nylon carry bag (available as an accessory). Keep the locator away from extreme heat or prolonged moisture.
  
  
• Calibration: The RD312 does not require routine calibration thanks to its auto‑sensitivity circuit. However, periodic functional checks using known targets help ensure continued performance.

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User Tips for Accurate Locating

• Harness the automatic gain feature. When you switch on the RD312 using the green ON/RESET button, the instrument automatically adjusts its sensitivity to the local environment. This adaptive gain enables accurate locating even near metal fences or under parked vehicles.
  
  
• Set up the locator for comfort and control. The RD312’s telescopic shaft extends and retracts, and the search‑head angle can be adjusted. Extending the shaft to a comfortable height and keeping the search head parallel to the ground helps you maintain a consistent sweep.
  
  
• Use the audio tone to pinpoint targets. A built‑in loudspeaker (or optional headphones) emits a variable pitch tone; the tone rises to its highest pitch when the search head is directly over the buried cover. Listening carefully for this peak pitch makes it easier to centre the instrument over the target.
  
  
• Manage gain when necessary. At power‑up the RD312 sets maximum sensitivity, but you can reduce gain manually if the signal is too strong. The unit’s auto‑gain reset feature allows quick re‑adjustment for varying conditions.
  
  
• Take advantage of rugged construction. The waterproof search head allows use in shallow water, so you can locate covers in flooded or rainy areas. The housing is weatherproof and unaffected by passing vehicles or small metallic debris such as coins and cans.
  
  
• Monitor the battery. The RD312 uses a single 6LR61 9‑V alkaline battery and can operate for roughly 30 hours at 20 °C. An audio “battery OK” indication warns when the battery needs replacing, so always start with a fresh battery and replace it when the tone weakens.
  
  
• Use headphones in noisy environments. Optional headphones cut out ambient noise and disable the loudspeaker while preserving the variable tone. They’re useful when locating in busy streets or near machinery.

By following these manufacturer‑recommended practices, operators can maximize the RD312’s accuracy and efficiency when locating buried metallic objects.

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Why Choose Eastcom Associates for the RD312?

Eastcom Associates, Inc. has been a trusted distributor of utility‑locating products in the Northeastern and Mid‑Atlantic United States since 1972. We stock a complete line of equipment for utility location, leak detection, fault location and pipeline inspection and are committed to offering superior service, selection and value. 

More than simply supplying underground utility locators, Eastcom helps protect people, assets and communities by bringing expertise and service to every excavation. This technical guide explains the RD312 metal cover locator – a rugged, easy‑to‑use tool designed to quickly locate buried or paved‑over metal covers and improve job‑site productivity.

Eastcom Associates prides itself on being the vendor of choice for customers and fostering an employee‑friendly culture that encourages growth. Our mission is to serve clients by supplying high‑quality products at competitive pricing while delivering exceptional customer service every day. 

Eastcom’s vision focuses on integrity, trust, commitment, service, teamwork and quality. With decades of experience and a deep understanding of customers’ challenges, Eastcom offers expertise, service and trusted solutions that keep every excavation safe. When you purchase an RD312 from Eastcom, you gain access to free training, responsive repairs and knowledgeable local sales managers covering the Northeast and Mid‑Atlantic regions.

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