M/D Totco GM6A / GM6AP Single Pointer Hydraulic Indicators

A single-pointer hydraulic indicator for mud pump pressure

The M/D Totco GM6A bracket-mount and GM6AP panel-mount single pointer indicators give quick, accurate checks on mud pump operation and help to detect a washed-out drill pipe or bit nozzle problems. The 6 inch fluid-filled gauge has a full 360 degree dial calibration, so the pointer sweeps the entire dial for the smallest pressure changes to be visible, and a high-pressure damper adjustment calms pulsation. The gauge can sit in the weight indicator box, in the driller console or locally at the mud pump.

Technical specifications

Selecting range, hose length and mounting

Choose the range from the maximum mud pump discharge pressure, and use the bracket version where the gauge is fixed on a pump or frame and the panel version for the driller console. Hose length matters: 50 ft is standard, and longer lengths are limited to some pressure ranges, so state the distance between the pressure tapping and the dial. The catalogue also shows 1:1 GM1006A and GM1007A single pointer indicators with a piston separator for accurate reading at up to 140 ft; those are different models and need their own enquiry.

Include the unit of measure, mounting style, hose length and the connection to the protector when quoting. The catalogue carries 2015 and 2017 copyright dates, so confirm that the model is current and which options are available before ordering.

How the M/D Totco GM6A hydraulic indicator works

A hydraulic pressure indicator of this type does not bring the process fluid into the gauge movement. A diaphragm protector at the pressure tapping separates the drilling mud from a clean fill liquid, and a hose carries the pressure signal to the dial, where a sensing element turns it into pointer movement. This arrangement keeps abrasive, viscous or solids-laden fluid away from the delicate parts of the gauge, and it lets the dial sit where the crew can see it instead of at the pump itself. The M/D Totco GM6A follows this principle in a bracket-mount form, and the GM6AP applies it to panel mounting. The damper adjustment smooths the pulsation that reciprocating pumps create, so the pointer can be read steadily during normal pumping.

Typical applications for the GM6A in drilling and well service

Mud pump pressure is one of the first signals a driller watches. A sudden fall in pump pressure can point to a washout, a lost nozzle or a leak, while a rise can indicate a restriction in the string or bit. A dedicated hydraulic indicator gives a direct, always-visible reading that does not depend on electronics, which is why this style of gauge is still found on land rigs, offshore rigs, workover units and service equipment around Oman and the wider Gulf. It also serves as an independent cross-check against electronic pressure transmitters and data-acquisition screens.

• Driller console or weight indicator box: panel mounting keeps the reading in the driller’s line of sight.
• Local reading at the mud pump: bracket mounting lets the pump operator verify discharge pressure on the spot.
• Secondary indication: a hydraulic dial remains useful when an electronic system is being serviced or has lost power.

GM6A selection checklist before you order

Before ordering the M/D Totco GM6A or the GM6AP, gather the following information so the quotation matches the real installation.

• Pressure range and unit: choose the capacity from the highest expected discharge pressure and confirm the unit your crew reads, whether psi, kg/cm2, kPa or MPa.
• Mounting style: bracket for pump or frame mounting, panel for a console cut-out.
• Hose length: measure the route from the tapping to the dial, including bends, and state it clearly.
• Protector and connection: confirm the tapping on the mud line and how the protector will thread into it.
• Fill and damping: note any special damping needs caused by pump type or stroke rate.
• Environment: mention the ambient conditions and any rig or area requirements that affect the instrument.

Installation, commissioning and maintenance practice

Mount the protector where it can be reached for servicing and where it sees true line pressure rather than a dead leg full of settled solids. Route the hose without sharp kinks, secure it so that vibration does not wear it, and avoid pulling it tight against moving equipment. When commissioning, bring pressure up gradually, watch that the pointer follows without sticking, and adjust the damper until pulsation is calm but real pressure changes still show promptly. Over-damping can hide a developing problem, so set it with the pump running at representative conditions.

In service, inspect the hose and fittings for leaks or abrasion, and check the dial for fluid loss or fogging. Compare the indicator with a reference gauge at planned intervals, and replace or recalibrate it if it drifts or the pointer no longer returns to zero. Keep the protector clean after mud service so that the diaphragm remains free to move.

Requesting a quotation for the M/D Totco GM6A

Seven Star LLC prepares quotations on request. Send the model, either GM6A or GM6AP, the pressure range and unit, the hose length, the quantity and a short description of the rig or pump application through the RFQ form on this page. Where you also need related M/D Totco instruments, list them in the same enquiry so the whole set can be reviewed together.

Documents and quotation

The NOV M/D Totco catalogue is available on this page, and further pressure products are under Pressure Instrumentation.