PulseGuard Ltd. and Inc.
PulseGuard Ltd. offers pulsation dampers | Please phone 44(0) 161-480-9625
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Fluid Flow Control Animations
Fluid Flow Control Animations


ASME Certification
BS EN ISO 9001 Certification
ASME Certification
BS EN ISO 9001 Certification




Hereinafter referred to as The Company


1. Customer's special Terms and Conditions may be accepted but only if the customer has written by letter to the company and has obtained the company's agreement in writing to the customer terms and conditions prior to the quotation, which will otherwise state a price and delivery based on these terms, as will our confirmation of your request for the supply of the goods or services.2. Quotation should only be requested for orders over 2,500 of any one size or an additional charge will have to be added to current price.3. Prices quoted are based on estimated or advised annual usage.
(a) Increases in the rate of call-off or total per annum (whichever shall be the lesser per annum rate) will be subject to a retrospective discount payable by us to you, for which you must apply when your quantity reaches another supply bracket.
(b) Decreases in the rate of call-off or total per annum will be subject to an automatic percentage increase in prices invoiced or additional invoice at the end of the supply period where your quantity falls to another supply bracket.(a) Price lists and quotations are only issued by the company in accordance with these Terms and Conditions and may be subject to alteration, in which case the company will notify regular customers and the price ruling at the date of despatch will be invoiced.
(b) Prices are for the goods only and do not include for drawings, transparencies, operating instructions, parts lists, survey, inspection, testing, certification, precharging, special labeling, marking, or painting, packing, carriage, duty taxes, or extra documentation, all of which will be charged extra.5. Every effort will be made to meet delivery dates which are quoted in good faith but the company will not accept responsibility for
the consequence of any delay resulting from late supply of raw materials or subcomponents or industrial action.

6. Ex-stock shall mean that the component parts are in stock. The 'build time' varies according to the type and quantity of unit ordered.7. Goods must be inspected and any complaints for claims as to quantity or specification must be made within 15 days of receipt of the goods or services.8. Un-negotiated peremptory unilateral cancellation of a contract or deferment of delivery of goods ordered by a customer will not be accepted by the company unless the cancellation or deferment is accompanied by a payment of 85% of the contract price confirmed.9. Orders of contracts offered will be accepted without acknowledgement and will be treated as an acknowledgement of these terms of sale and our confirmation of your request for supply of our goods or services does confirm these terms.10. Net payment for goods must be received in our possession within 35 days of invoice date unless specific agreement has been made to the contrary. An invoice shall also be the statement for that invoice, invoice date is the date the goods pass our in-house Hydrotest.11. The literature in the company's catalog is full and comprehensive. The company, therefore, reserves the right to make a charge for copies of drawings or any additional information, viz, certified drawing, building under survey, construction to foreign codes, certification of strength calculations, manufacturing reports, bar charts, production planning schedules, details of sub-orders, special maintenance manuals.12. Whereas every effort will be made to furnish accurate information, the company shall not be liable for any variation or difference between weight, dimensions and general specification of the packing in which delivery is made and any description of such packing previously made.13. All drawings, sketches, vessel data sheets and other non catalog graphic representations of the product are the property of the company and may not be reproduced, copied, shown to third parties or passed on without the company's permission and shall be returned to the company in the event of notification to you by the company of your alleged breach of contract. The company accepts responsibility for any Patent infringements in the manufacture only of the goods. All tooling is the sole property of the company. Its costs are amortized over existing or future sales. No additional charges will be made unless specific alterations are requested. The company reserves the right to charge for any subcontract material contracts entered into in good faith which have been influenced by your estimated annual usage in the event of your actual usage falling below the estimate.
14. The company shall not be liable to make right any malfunction of goods unless the temperature, contamination, fluid, environment, frequency of operation, maximum and minimum system pressure and flow rate have been specified on the order.15. Service visits cannot be undertaken unless the units have been paid for and are suitably mounted, for example, so that the socket head cap screws which attach the units to their subplates are easily accessible.16. Prices quoted by the company are not costed on the basis of including consequential loss insurance, prices including these costs should be requested if this is important to customers or their end users therefore the company has no liability for consequential loss, neither has the company any liability for carriage on units which customers may wish to return. The company shall not in any event be liable for costs of stripping out or re-installation within any system that it has not designed and supplied itself.17. All units are covered by one year's guarantee, running from the date that the company's products enter use or 18 months from the date of despatch or shipment, on labor and materials in our works but only if all the above conditions have been accepted and observed.18. Suitability for purpose.19. The issue of any credit notes shall not vary these terms of supply.20. The company cannot accept that the delivery date shall be of the essence of the contract although every effort will be made to meet your requirements and any major causes of hold up will be notified to you.21. The company will charge interest of 18% per annum on payments which are overdue, i.e. from the 35th day after invoice date.22. The company does not accept any set off, invoices must be paid in full and questions of credit will be covered by credit notes.23. The company reserves the right to suspend deliveries in the event that credit limit of the customer has been reached or payments are not being received within 35 days on invoice date.24. Passing of Title and Risk
(1) From the time of delivery the Goods shall be at the risk of the Customer who shall be solely responsible for their custody and maintenance but, unless otherwise expressly agreed in writing, the Goods shall remain the property of Membranoflex Limited (trading as Liquid Dynamics and often referred to as L.D.i. (a verbalization of the company's Logo)) hereinafter referred to as the Company until all payments under the contract for the Goods have been made in full and unconditionally. Whilst the ownership by the Company continues, the Customer shall keep the Goods separate and identifiable from all other goods in its possession as bailee for the Company.
(2) In the event of any resale by the Customer of the Goods the beneficial entitlement of the Company shall attach to the proceeds of sale or other disposition thereof so that such proceeds or any claim therefore shall be assigned to the Company and until and subject to such assignment shall be held on trust in a separate identified account for the Company by the Customer and such proceeds shall not be mingled with other moneys or paid into any overdrawn bank account and shall at all times be identifiable as the Company's moneys.
(3) In the event of failure to pay the price in accordance with the Contract, the Company shall have power to resell the Goods, such power being additional to (and not in substitution for) any other power of sale arising by operation of law or implication or otherwise and for such purpose the Company and its servants and agents may forthwith enter upon any premises or land occupied or owned by the Customer to remove the Goods.
(4) Pending payment of the full purchase price of the Goods the Customer shall at all times keep the Goods comprehensively insured against loss or damage by accident, fire, theft, and other risks usually covered by insurance in the type of business carried on by the Customer in an amount at least equal to the balance of the price for the same from time to time remaining outstanding. The policy shall bear an endorsement recording the Company's interest. TC2/18/1/81
Nota Bene Rev.3/9/86
The designation of the unit and the parameters governing its selection are to be found in the company's literature.
The formulae and technical parameters disclosed in the sales literature are for your guidance only and we earnestly suggest that unless
you are absolutely certain of the designation of the units you require that you complete and sign our Questionnaire.
Hydropneumatics products supplied by us are normally designed to be precharged with clean dry oxygen free Nitrogen (OFN). Warning
In view of the Occupational Safety and Health Legislation of 1970 we advise you to order units with the gas rupture disc for safety overload protection at between 1.7X and 3X working pressure. The ratio between the designed burst pressure and working pressure of any industrial unit pressure may be as high as 4.4:1 and fail-safe leak off pressure and working pressure is 4:1. Units are thus designed to lose their energy storing gas before a total failure pressure can be reached. They must not be clamped or mounted in any way which will restrict this fail-safe, but this in no way relieves the necessity to install a direct acting relief valve which must be able to fully open by 1:1x working pressure adjacent to any pressure vessel. The maximum stated working pressure must not be exceeded at any time.
One unit per batch of bodies or one percent of like units produced are tested to destruction. Units are generally inspected for corrosion at least every 20 months depending on environment.
Each unit is pressure tested to 1.5 working pressure, before shipping, and is also gas leak tested. Any additional over-pressurization is expressly not permitted under the guarantee or products liability policy.SUITABILITY FOR PURPOSEI. When dealing with Applications or Project Engineering, it is assumed that they are aware of what is normally expected from hydro-pneumatic and/or pressure products and their parts of any particular type. In such dealings, the company's engineer and sales personnel merely state the nominal volume, the maximum working pressure and the port size of the unit involved; there is no guarantee of the performance or safety of the unit supplied under such circumstances unless the company's questionnaire has been fully completed and signed.
II. When dealing with procurement executives and their assistants we must assume that they have been fully briefed by their engineering staff.
III. In cases where a total concept design study does not appear to have been undertaken. If the customer requires a guarantee on the performance or a certificate on the safety of the unit, a full disclosure of all the facts known by the customer and his user and all the sources of information which will help to complete the disclosure, must be given to the company.
Pressure products are generally capable of exhausting or accepting their full rated volume at any rate of flow entirely dependent upon the pressure rise or fall in the system to which they are attached. Their specific performance is, therefore, dependent on:-
PARAMETERS1. The liquid to be used.
(a) The information given in the company's catalog, sales literature, drawings, quotations, or by its sales and engineering personnel as to
compatibility is offered only for your convenience, consideration, investigation and verification. The company and/or its personnel cannot
accept liability for chemical attack as our clients or their consulting engineers being main system engineers or main component contractors are
taken to be far more conversant with the compatibility of materials to their process, than this company's. Advice passed on by us as a result
of our membership of Rubber & Plastic Research Association shall not incur us OR that association any liability. In the event of any doubt
we will be happy to supply at a nominal charge samples of suggested materials of construction for immersion/temperature/compatibility tests
to be carried out.
(b) Its specific gravity.
(c) Its viscosity.
(d) The temperature range over which it works.
(e) The acidity - alkalinity - abrasiveness - solvent nature and general compatibility.
2. The fluid pressure supply.
(a) Its flow rate or multiples of flow rate.
(b) The time taken for its unloading and loading valves to respond.
(c) The pressure differential which it is capable of creating.
(d) The maximum pressure to which the direct action relief valve or burst disc can be set and its position in the system.
3. The pipework or ducts which are connected to it.
(a) Its length or multiples of length.
(b) Its diameter or multiples of diameter.
(c) The flow friction that it may create, dependent upon the number of bends, elbows, etc.
4. The position of the unit
(a) Whether it is fitted into the duct or
(b) Whether it is 'T'd' off from the duct.
5. The draw off from the system
(a) The number of outlets that are drawing off.
(b) The pressure drop/flow rate which occurs at these outlets.
(c) The instances of these requirements.
(d) The total cycle time relationship in which these instances occur.
(e) Any dwell time between cycles.
(f) The speed with which the outlet control valves work.
(g) The number of times per annum that the system will be shut down.
6. Boyle's Law (isothermal) or adiabatic (dependent upon the flow rate involved).
(a) The total gas volume contained in the units.
(b) The total gas volume contained in the units plus the total gas volume contained in any attached back up vessel system.From the above parameters, the proposed supplier will draw a suggested design specification which may be altered, re-drawn or amended by the customer, but must be signed by the customer, after which it shall form the basis of the supply contract between the companies or individuals involved.
The above procedure is merely normal practice for the supply of pressure vessels to the codes which have been drawn to cover them. As there is no code in existence specifically covering pulsation dampers, shock alleviators, pump controllers, liquid line silencers, accumulators, sample bombs, and similar hydro-pneumatics equipment, this has been compiled, it is not in any way mandatory, but it forms part of this Company's Standard Terms and Conditions of Supply.

Schematic of "The safety seal" method of pressure

Membranoflex LDI contact information

See page 203 of "Hydraulic Handbook" 7th edition and pages 169/170 of 8th edition
(Courtesy of Trade & Technical Press Ltd.)

The Health & Safety at Work etc. Act 1974 lays a Duty on Users to disclose "adequate information" about the use to which they
wish to put a product and lays a duty on manufacturers to ensure safe design and construction of items when properly used - as under Chapter 37, paragraph 6(1) a, b, and c.

We trust this SAFETY DESIGN CODE will be of help to you and enclose a copy of our specification questionnaire which should be completed, prior to quotation for supply as necessary, to enable us both to comply with the act.
In accordance with the most stringent requirements applied in the following countries by the listed authorities, the following
specification has been provisionally compiled.

Belgium - Associated Industrial Belgique (A.I.B.), France - Bureau de Mines, A.P.A.V.E., Germany - T.U.V., Italy -
A.N.C.C., Sweden - "Swedish Steam Users" and "T.R.C.", Switzerland - S.V.B.D., U.S.A., Canada, and Japan -
A.S.M.E. VIII, Div. 1., A.S.M.E./A.N.S.I. B31.3a, Holland - "Stoomwesen", U.K. - A.S.M.E. VIII, Div. 1 AND BS 5500.

1) The units should be capable of losing the energy they store by virtue of the gas within them prior to reaching destruct pressure.
The incorporation of a Gas Burst Disc, our designation G.B.D. at the end of the Part Nbr., is one method of accomplishing this.
2) The units must be manufactured in such a way that both the tactile and close visual inspection can be made without difficulty at
any place within the units, this enables stress corrosion and pitting to be detected when units are re-pressure tested annually or as appropriate.
3) The units shall not have less than 3:1 gas vent pressure to design pressure ratio, so that potential energy storage capability is lost at a lesser pressure than final failure pressure.
4) Units shall not have less than a 4:1 safety factor, i.e. burst pressure to design pressure, except when specifically required to be in accordance with A.S.M.E. B31.3a (pipefittings), BS5500 or others.
5) Design pressure shall not be less than 10% above maximum working pressure, to allow for the normal inconsistencies of system pressure relief valves.
6) There shall be an allowance for corrosion to 10% of wall thickness, or 3mm if required by user under A.S.M.E. Code for
Unfired Pressure Vessels.
7) Allowance shall be made in the design calculations for any stress raisers, example screw thread closures, or any that could be caused by scratching of the bore of the unit, possibly resulting from malfunction of sliding parts, example pistons without
bearing pads.
8) Units shall be type tested to destruction, and 1% or one off per batch, made from the same material tested in the event of any engineering change.
9) The work/shop order number shall be recorded on the material analysis and physical properties certificate of the material used in the construction.
10) The units shall be designed in such a way that it is impossible to begin to disassemble them until the pressure has been vented from within them.
11) The complete accumulator/damper including all bladder/diaphragm/sealing members assembly shall be pressurized to 1-1/2 times working pressure before despatch/shipment.
12) They shall be made from sufficiently ductile material to enable the result of any overpressurization to a dangerous level to result in a measurable retained deformation after they have been depressurized.
13) Any unit of a welded construction shall be pressurized to twice it's working pressure where not specifically prohibited by Code and shall be de-rated by 30% of it's calculated maximum working pressure for any cyclic duty exceeding 1,000 p.a.
14) Accumulators/dampers must be designed to retain above safety factors in the event of gas overpressurization, e.g. due to a local fire.
15) Every accumulator/damper must be used with a pressure relief valve so positioned as to make it impossible to isolate the
accumulator/damper from the said relief valve.
16) A bleed valve shall be so positioned in relation to the accumulator, its non isolatable relief valve, and its isolation valve, that it is impossible for the bleed valve to be isolated from any pressure remaining within the accumulator so that in the event of the bleed valve being opened it cannot fail to empty any remaining pressurized fluid from the accumulator.

PATENTS: 1099388, 1070366, 2033166, 4206167, 4735567, 2408568, 4965068, 622774, 733466, 734436, P1775721, 0, H63915/47FBG, H61985 (P1627823.2.), H58185/58 AGBB, 1518045-798112

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Return to the beginning of PulseGuard, pulsation dampeners


Selecting Pulsation Dampeners for Different Pump Systems.
Flow through pulsation dampers are at least 3 times more efficient than T off line accumulators.
Dampeners that do, flow goes through, but pressure pulsation does not.
PulseGuard Pulsation DampersThe Smooth Flow People

Call Toll Free 1-888-DAMPERS (326-7377) / See also: Pulsation-Dampeners.com for a pulsation dampener.

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