The threat · Equipment unbolted and stolen at remote sites?

D-Bolt

Name: D-Bolt
Brand: D-FENCE

A strain-gauge sensor built into the nut: any attempt to loosen, bend or cut the bolt raises an alarm with its location.

Patented

M14–M22 nutsIP65 / IP6810-year sensor warranty

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DatasheetPDF · 268 KB Tender specification textCopy text

Render: foot of a lattice pylon with a D-Bolt sensing nut on the anchor bolt and armoured cable to an open control box on the leg

Stop equipment theft at the first loosened bolt.

Generators, pumps, valves, pylons and cabinets often stand alone at remote sites, held in place by bolts. That is where thieves and vandals start.

Invisible to the thief

The sensing nut looks like every other nut on the structure, so there is nothing to spot.

One bolt per asset

A single D-Bolt protects a generator, pump, valve or cabinet, which keeps large deployments cost-effective.

Alarm with location, anywhere

Wireless, GPRS, SMS or GSM, or dry contact and RS485 into your control room.

D-Bolt turns one of those bolts into a sensor. A D-FENCE strain-gauge element built into the nut fits standard sizes from M14 to M22 and looks like any other nut on the structure. Any attempt to open, loosen, bend or cut it changes the pressure on the sensor and triggers the alarm.

The electronic control card sends the alarm and its location over wireless, GPRS, SMS or GSM, or through dry contacts and RS485 into your security system, and can switch on CCTV, a siren or floodlights on site. One bolt per protected unit is enough, which keeps the system cost-effective.

From the first touch to the right response.

Sensing nut fitted
A D-Bolt replaces a standard nut (M14–M22) on the asset.
Tamper detected
Opening, loosening, bending or cutting changes the pressure on the strain gauge.
Control card acts
It switches on CCTV, a siren or a floodlight on site and fires its transmitter.
Instant notification
The alarm and its location reach the control room, D-Command Control or a mobile app.

Seen in full.

Every image opens full size. Product sheets are shown whole, exactly as D-FENCE publishes them.

Render: close-up of a generator base frame with a D-Bolt sensing nut on the mounting bolt and its open control box; inset of the nut — **FIG. 01**Generator: sensing nut on the frame, control box beside it

D-Bolt sensing nut with a serial label on the flange bolt of a blue water valve, armoured cable running to the control card — **FIG. 02**Field installation on a valve flange

The D-Bolt sensing nut: a stainless hexagonal nut with D-FENCE marking and a sealed cable gland — **FIG. 03**The sensing nut

Render: base plate of a mast in hard sunlight, with a D-Bolt on one anchor nut and the control box on the mast — **FIG. 04**Mast base: the anchor nut is the sensor

Render of a lattice pylon base on a concrete pad with a cabinet beside it; callouts show the strain-gauge sensor and D-Bolt sensing nuts wired to control boxes at the foot of the pylon — **FIG. 05**Pylon base: where the sensors sit

Cut-away blue valve on a white pipe fitted with a D-FENCE control card and a red local beacon, at an exhibition — **FIG. 06**Valve demonstrator with control card and local beacon

Render of a fenced desert telecom compound with lattice tower, cabinets and solar panel; callouts show D-Bolt, a 360° camera, a pressure strip on the gate and a sensor post — **FIG. 07**Layered protection of a remote telecom site

Render of a tanker, a container trailer and a van; insets show D-Bolt sensors at the container door and the control card — **FIG. 08**Trucks, tankers and containers

D-Bolt technical specifications sheet with photos of the control card and two sensing nuts — **FIG. 09**Technical specifications

Specifications & documents.

SpecificationsD-Bolt

Sensor dimensions: 40 × 18 mm (diameter × height)
Sensor weight: 130 g
Nut sizes: M14–M22
System unit dimensions: 124 × 67 × 24 mm, 60 g
Bolts per control card: Up to 2
Trigger force: Custom set per project (spec sheet: alarm at 10 kg and above)
Dry contact: N.O. & N.C.
Power supply: 12 VDC
Current consumption: 23.333 mA
Communication output: RS485; wireless, GPRS, SMS or GSM transmitter
Operating temperature: −25 °C to +72 °C
Storage temperature: −55 °C to +80 °C
Humidity / protection: 95 %, IP65 / IP68
Corrosion: Anti-corrosion treatment per MIL-T-152; all parts stainless steel or aluminium
EMI & RFI: According to MIL-STD-461, 462
False alarm rate (catalogue specification): Less than 1 per km per 3 months
MTBF (sensor): 4.7 × 10⁸ h
MTTR: 30 min
Warranty: 10 years on the sensors

Specification text, ready for your tender.

Copy it into your specification. It describes the system by what it must do, so any alternative has to meet every point.

D-BoltTender specification textDatasheet

General
The system shall be D-Bolt by D-FENCE Electronic Fencing and Security Systems Ltd. (ISO 9001:2015 certified quality management), or an approved equivalent that meets every requirement in this section.
Function
A strain-gauge sensor built into the nut: any attempt to loosen, bend or cut the bolt raises an alarm with its location.
The system shall provide
- Sensor inside the nut: Strain gauge integrated into nuts of different calibres, M14–M22.
- Invisible and tamper-proof: Looks like any other nut on the structure; water resistant.
- Detects loosening, bending, cutting: Any attempt on the bolt changes the pressure and raises the alarm.
- Alarm with location: Wireless, GPRS, SMS or GSM transmitter on the control card.
- Local activation: Switches on CCTV, a siren or a floodlight at the asset.
- One bolt per asset: A single sensing bolt protects each unit, keeping large sites cost-effective.
Technical requirements
- Sensor dimensions: 40 × 18 mm (diameter × height)
- Sensor weight: 130 g
- Nut sizes: M14–M22
- System unit dimensions: 124 × 67 × 24 mm, 60 g
- Bolts per control card: Up to 2
- Trigger force: Custom set per project (spec sheet: alarm at 10 kg and above)
- Dry contact: N.O. & N.C.
- Power supply: 12 VDC
- Current consumption: 23.333 mA
- Communication output: RS485; wireless, GPRS, SMS or GSM transmitter
- Operating temperature: −25 °C to +72 °C
- Storage temperature: −55 °C to +80 °C
- Humidity / protection: 95 %, IP65 / IP68
- Corrosion: Anti-corrosion treatment per MIL-T-152; all parts stainless steel or aluminium
- EMI & RFI: According to MIL-STD-461, 462
- False alarm rate (catalogue specification): Less than 1 per km per 3 months
- MTBF (sensor): 4.7 × 10⁸ h
- MTTR: 30 min
- Warranty: 10 years on the sensors
Detection sequence
1. Sensing nut fitted: A D-Bolt replaces a standard nut (M14–M22) on the asset.
2. Tamper detected: Opening, loosening, bending or cutting changes the pressure on the strain gauge.
3. Control card acts: It switches on CCTV, a siren or a floodlight on site and fires its transmitter.
4. Instant notification: The alarm and its location reach the control room, D-Command Control or a mobile app.
Submittals
Before installation, the contractor shall submit the manufacturer's datasheet, the installation instructions and the zone layout for approval.

D-Bolt | Tender specification text

1. General
The system shall be D-Bolt by D-FENCE Electronic Fencing and Security Systems Ltd. (ISO 9001:2015 certified quality management), or an approved equivalent that meets every requirement in this section.

2. Function
A strain-gauge sensor built into the nut: any attempt to loosen, bend or cut the bolt raises an alarm with its location.

3. The system shall provide
- Sensor inside the nut: Strain gauge integrated into nuts of different calibres, M14–M22.
- Invisible and tamper-proof: Looks like any other nut on the structure; water resistant.
- Detects loosening, bending, cutting: Any attempt on the bolt changes the pressure and raises the alarm.
- Alarm with location: Wireless, GPRS, SMS or GSM transmitter on the control card.
- Local activation: Switches on CCTV, a siren or a floodlight at the asset.
- One bolt per asset: A single sensing bolt protects each unit, keeping large sites cost-effective.

4. Technical requirements
- Sensor dimensions: 40 × 18 mm (diameter × height)
- Sensor weight: 130 g
- Nut sizes: M14–M22
- System unit dimensions: 124 × 67 × 24 mm, 60 g
- Bolts per control card: Up to 2
- Trigger force: Custom set per project (spec sheet: alarm at 10 kg and above)
- Dry contact: N.O. & N.C.
- Power supply: 12 VDC
- Current consumption: 23.333 mA
- Communication output: RS485; wireless, GPRS, SMS or GSM transmitter
- Operating temperature: −25 °C to +72 °C
- Storage temperature: −55 °C to +80 °C
- Humidity / protection: 95 %, IP65 / IP68
- Corrosion: Anti-corrosion treatment per MIL-T-152; all parts stainless steel or aluminium
- EMI & RFI: According to MIL-STD-461, 462
- False alarm rate (catalogue specification): Less than 1 per km per 3 months
- MTBF (sensor): 4.7 × 10⁸ h
- MTTR: 30 min
- Warranty: 10 years on the sensors

5. Detection sequence
5.1 Sensing nut fitted: A D-Bolt replaces a standard nut (M14–M22) on the asset.
5.2 Tamper detected: Opening, loosening, bending or cutting changes the pressure on the strain gauge.
5.3 Control card acts: It switches on CCTV, a siren or a floodlight on site and fires its transmitter.
5.4 Instant notification: The alarm and its location reach the control room, D-Command Control or a mobile app.

6. Submittals
Before installation, the contractor shall submit the manufacturer's datasheet, the installation instructions and the zone layout for approval.