Concrete vibrator (internal immersion vibrator)

01

Choose head diameter, hose length and power

Nantong Change Electric Tools lists its CV-230A concrete vibrator at 2,300 W rated input, 220 V or 110 V, a no-load speed of 4,000 r/min, a maximum poker hose diameter of 60 mm and a maximum hose length of 6 m, and states that its vibrators carry TÜV, CQC and 3C certifications. [2]

Editorial calculation: 4,000 r/min is about 67 revolutions a second at no load; ask the supplier for the vibration frequency and amplitude at the head when immersed in concrete, since the no-load motor speed alone does not give them. A 6 m hose lets the operator stand back from the placing point; for a deep wall, check that hose length covers the lift depth plus the reach from the deck. [2]

Editorial note: choose a head small enough to pass between reinforcing bars and large enough for the member; give the supplier the clear bar spacing and member sizes.

Give the supplier the members (slabs, walls, columns, beams), clear spacing between bars, lift depths, concrete mix and slump, power available (single-phase, generator, engine drive), hose length needed, number of units and standby units, head protection needs near coated rebar, and certifications required.

02

Compare high-frequency heads by centrifugal force and zone of influence

OLI's VN (Standard Line) and VNP (Professional Line) electric high-frequency internal vibrators, as listed in its distributor Jamieson Equipment's catalogue, all run at 12,000 vibrations per minute and are supplied with a 16 ft protection hose and a 33 ft electric cable with hand switch. OLI states that the VNP line develops higher centrifugal forces and has a shaft with four bearings plus a needle bearing for extra-heavy-duty jobs, and that the VN line has thermistor motor protection. [4]

All values in the table are from the OLI listing; centrifugal force is printed in kilograms (kgf). [4] Editorial calculation: 12,000 vibrations per minute is 200 Hz, three times the 67 Hz that the CV-230A's 4,000 r/min no-load speed would give if one revolution produced one vibration. At the same 50 mm head, the professional VNP 50 lists 380 kgf against 300 kgf for the VN 50 (about 27% more) and a 65 cm against a 60 cm influenced zone, for 15.0 A against 8.0 A of current. Converted, 300 kgf is about 2.9 kN and 740 kgf about 7.3 kN. [4] [2]

Use the influenced-zone figure only as the maker's guide: the TxDOT items above still require insertion at systematically spaced points through the full lift depth, and the CRD-C 521 test checks frequency and amplitude on each delivered unit. Ask whether a high-frequency head needs a separate frequency converter or runs direct from site power, and how many heads one supply can drive. [1] [3]

03

Vibrate concrete as the specification requires

Texas DOT's 2024 Item 420 (Concrete Substructures) requires concrete to be consolidated with immersion-type vibrators, not form- or rebar-mounted vibrators unless approved for steel forms; vibration must start immediately after deposit, at systematically spaced points to work concrete around reinforcement and into corners, with the vibrator inserted vertically where possible, through the full depth of each lift, "allowing the vibrator to penetrate several inches into the preceding lift". Vibrators must not be used to move concrete or be dragged through it, and along construction joints the vibrator runs close to, but not against, the joint. [1]

Item 421 equipment requirements call for immersion-type vibrators, at least one standby vibrator for emergencies, and heads covered with a rubberized or elastomeric cover when used near epoxy-coated reinforcing steel. The same specification book's provisions for prestressed beams and piling call for high-frequency internal vibration by trained personnel with proper timing and spacing. [1]

Editorial note: plan the number of vibrators from the placing rate and the number of insertion points per lift, then add the standby unit the specification requires.

04

Compare what suppliers offer

Suppliers linked to this page list concrete vibrators; each card links to the page reviewed.

The suppliers reviewed list electric and engine-driven concrete vibrators with other concrete and power tools; ask each for head diameters, hose lengths, motor power and voltage, vibration frequency and amplitude at the head, rubber-covered heads and certifications.

05

Test vibrator frequency and amplitude before accepting units

The US Army Corps of Engineers test method CRD-C 521-81, issued 1 Sept. 1981, gives a field or laboratory procedure for checking the frequency and amplitude of form and internal concrete vibrators, electric or air-driven. Frequency is read with a tachometer held against the vibrator, or against the hose on an air vibrator; for an internal vibrator the Corps says the reading should be taken just before the vibrator is withdrawn, when it runs at its fastest speed in concrete. Amplitude is read with an optical wedge: on an internal vibrator two wedges are attached, one near the tip and one near the back end of the head, the head vibrates in air, and the result is the average of the two readings, taken as peak amplitude (half the peak-to-peak displacement). [3]

The Corps states that, with care, the optical wedge reads to an accuracy of about 0.005 in. (0.13 mm); its illustration shows a reading of 0.055 in. (1.4 mm). The test report lists vibrator type, model, serial number and maker, test date, frequency in air and frequency in use in VPM (Hz), amplitude at each point with locations identified, average amplitude, and changes since the preceding test. The method states that data are not available to estimate its precision or accuracy. [3]

Editorial note: ask each supplier to quote head frequency both in air and in concrete, and amplitude measured on the head itself, rather than the no-load motor speed alone. Write the test and its report fields into the purchase order, run the same test on each delivered unit and on the standby unit, and keep the readings so that later tests on the same serial number show wear of the head, shaft or motor.

06

Trace the vibrator components

This is a functional reference built from the sources cited; it is not one maker's design.

07

Fill the specification fields with values for your pours

A concrete vibrator quotation needs values for your pours. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

08

Send the pour, member and power data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Members: [type; sizes; bar spacing]
Pours: [lift depth; placing rate]
Concrete: [mix; slump]
Vibrator: [head size; hose length; power]
Power: [voltage; generator; engine]
Specification: [immersion type; standby; covered heads]
Certifications: [electrical safety]

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