M/D Totco TRU-VUE GM14 Unitized Pressure Gauge

A large-dial mud pressure gauge for standpipe and manifold service

The M/D Totco TRU-VUE GM14 is a unitized pressure gauge for drilling and well-service pressure monitoring. NOV states that it is the only mud pressure gauge that can be read easily from 75 feet and more away, a manufacturer claim made in its catalogue. A rugged bourdon tube and movement indicator is described as suited to standpipe and local pressure manifold applications, with use also noted in blowout prevention, cementing, fracturing, acidizing and gravel packing trucks.

Technical specifications

Choosing the range and connection

Pick the capacity so that normal working pressure sits well inside the scale, since the catalogue offers six psi ranges from 1,000 to 15,000 psi and metric scales. The threaded 2 inch male NPT connection covers most manifold and standpipe tapings, while the optional API 6BX flange is for special high-pressure applications. The gauge is fluid filled and has an adjustable damper, so damping can be tuned to the pump pulsation at the point of use. Because the diaphragm cup and check valve are replaceable, fluid loading and servicing can be done at the rig site.

Send the pressure range and unit, the connection type, the fluid and the mounting position when requesting a quotation. The catalogue carries 2015 and 2017 copyright dates, so confirm that the model is current and which options are available before ordering.

How a bourdon-tube gauge such as the GM14 works

Inside the case of a bourdon-tube gauge is a curved, flattened metal tube that is closed at one end. When pressure enters the open end, the tube tries to straighten, and the small movement of the closed tip is amplified by a gear train into the rotation of the pointer. Because the tube responds directly to pressure, the design is simple, robust and needs no power supply, which is why it remains the standard local indicator on drilling and well-service equipment. The GM14 adds a fluid-filled case and an adjustable damper to this proven principle, so the pointer stays steady even when the pressure pulses with every stroke of a reciprocating pump.

Where the TRU-VUE GM14 is used

• Standpipe pressure on drilling rigs, where the driller watches circulating pressure continuously.
• Local pressure manifolds on the rig floor and in the pump house.
• Cementing, fracturing and acidizing units where a large, easily read dial is useful at the unit.
• Blowout prevention and well-control panels as listed on this page.

Selecting range, connection and damping

Choose a capacity so that the normal working pressure sits comfortably within the scale rather than near the end, and so that the peak pressure of the system does not exceed the gauge range. A gauge that is run close to full scale for long periods wears faster and gives less useful resolution in the working band. Decide the unit at the same time, because psi, bar, kPa and MPa scales are offered and a mix of units on one rig leads to reading errors.

The standard threaded connection suits most tappings, while the optional flange is for special high-pressure arrangements. Set the damper so that the pointer is steady but still follows real pressure changes quickly; too much damping hides a genuine pressure drop or spike from the operator. Before you ask for a quotation, collect these details:

• the working and maximum pressure and the unit you need;
• the connection type and the position of the gauge on the line;
• the fluid at the gauge, such as drilling mud, cement or acid;
• whether the gauge will be exposed to vibration, shock or low temperature;
• the quantity and any spare parts for servicing at the rig.

Installation and routine care

Fit the gauge so that the dial is visible from the working position, and use the case flats, not the case itself, when tightening the thread. Isolate the gauge with a valve where the system allows it, so that it can be removed and checked without shutting down the line. Never exceed the scale limit, and release pressure before removing it. Check the pointer at zero when the line is at rest, look for fluid loss from the filled case, and clean the diaphragm cup and check valve when they have been exposed to mud or cement. Compare critical gauges against a reference gauge at intervals set by your maintenance plan, and replace any that no longer agree.

Reading the gauge correctly in service

Read the dial from directly in front, because looking from an angle introduces a parallax error on a large scale. Note the pressure at which each pump runs under normal conditions so that an unusual reading is recognised at once. If the pointer sticks, jumps or fails to return to zero, remove the gauge from service and have it checked rather than relying on it for a well-control decision.

Requesting a quotation for the M/D Totco TRU-VUE GM14

Seven Star LLC prepares quotations for the GM14 on request. Send the pressure range and unit, the connection, the service fluid and the quantity through the RFQ form on this page.

Documents and quotation

The NOV M/D Totco catalogue page for the GM14 is in the document on this page. Related pressure products are listed under Pressure Instrumentation.