Prosecution Insights
Last updated: April 19, 2026
Application No. 18/573,743

METHOD OF FILTRATING LIQUID, AND FILTRATION APPARATUS FOR FILTRATING LIQUID

Non-Final OA §103
Filed
Dec 22, 2023
Examiner
SPIES, BRADLEY R
Art Unit
1777
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Renasys AS
OA Round
1 (Non-Final)
74%
Grant Probability
Favorable
1-2
OA Rounds
2y 6m
To Grant
95%
With Interview

Examiner Intelligence

Grants 74% — above average
74%
Career Allow Rate
596 granted / 807 resolved
+8.9% vs TC avg
Strong +21% interview lift
Without
With
+20.9%
Interview Lift
resolved cases with interview
Typical timeline
2y 6m
Avg Prosecution
35 currently pending
Career history
842
Total Applications
across all art units

Statute-Specific Performance

§101
0.6%
-39.4% vs TC avg
§103
45.0%
+5.0% vs TC avg
§102
21.3%
-18.7% vs TC avg
§112
19.0%
-21.0% vs TC avg
Black line = Tech Center average estimate • Based on career data from 807 resolved cases

Office Action

§103
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claims 1-8 and 10-18 rejected under 35 U.S.C. 103 as being unpatentable over the combination of Van Schie et al (WO 2021/101379 A1) and Dieter (DE 2816378 A1). With respect to claims 1 and 10, Van Schie teaches a method and apparatus for filtration using a belt filter [Abs] which includes filtering a liquid through a filter element (the belt filter) and into a downstream collection volume, and teaches that the collection volume can advantageously be substantially closed (closed to atmosphere) to create an underpressure on the filter element which enhances filtration by suctioning liquid through the filter element; further, the collection volume is itself controlled by way of a liquid pump and a gas (vacuum) pump for controlling the underpressure [pg. 11, lines 8-21]. The system may further include level sensors and pressure sensors to monitor the filter and the collection volume [pg. 11 line 30-pg. 12 line 9] and includes a control unit programmed to control e.g. the gas and liquid suction pumps based on these measurements [pg. 12 lines 10-18]. Van Schie therefore teaches a method and apparatus including a filter as claimed, a downstream collection volume as claimed, and operational steps (or control unit programming) to control a collection volume liquid flow out from the collection volume as well as control a gas flow out from the collection volume. As defined by the claim language, such control of the outflows necessarily constitutes control of the differential pressure and the passing time of the filtration. Additionally, as above, Van Schie explicitly desires to control the differential pressure (underpressure) and, regarding passing time, the purpose of such differential pressure control is explicitly stated as being to realize the filtration more quickly (i.e. reduce passing time). Van Schie essentially differs from the instant claimed inventions in that Van Schie does not disclose an outlet line between the filter element and the collection volume. Dieter teaches a suction filter of the belt type [Abs] in which a suction chamber beneath the filter is connected via a suction pipe (18) to a separate collection tank (19) which is substantially closed and used to generate an underpressure via vacuum pump (22). Filtrate from the tank is discharged via a separate liquid suction line (23) [0027]. The system is controlled to maintain the desired level of vacuum by a suitable gauge (21). Dieter essentially differs from the instant claims in that Dieter is silent to controlling the outflow of liquid from the tank or to specific control logic/a control unit coordinating multiple flows and sensors and the like. It would have been obvious to one of ordinary skill in the art to modify the system and process of Van Schie to include an outlet line between the filter space and the collection tank for reasons discussed by Dieter, in particular because this allows for provision of a check valve (19) on the outflow line which prevents any undesired backflow [0026] and, more particularly, because separating the filter equipment from the suction tank via the outlet line allows for the filter equipment to be produced with an extremely low profile which allows for convenient placement in various industrial applications [0014]. Additionally or alternatively, it would have been obvious to one of ordinary skill in the art to modify the system and process of Dieter to include control of the outflow of liquid and control unit/logic to coordinate the outflows and various sensors in order to gain the benefit of better maintaining operating conditions to optimize the desired pressure and flowrate values and the like, and to ensure that the filter is cycled at appropriate times when clogged or the like. In either combination, the claimed invention would have been obvious to one of ordinary skill in the art. PNG media_image1.png 499 342 media_image1.png Greyscale PNG media_image2.png 629 464 media_image2.png Greyscale With respect to claims 2, 11, and 12, Van Schie teaches that the control unit may control the filter speed of the filter element by controlling a drive element (motor) based on measured values such as pressure or liquid level values [pg. 12 lines 10-19]. The drive element is preferably an electric motor [pg. 10 lines 19-33]. Dieter similarly teaches a motor (7) and roller (5) to move the belt-type filter [0033] which cycle can be triggered by pressure thresholds [0030]. With respect to claims 3 and 13, at least Dieter teaches that the action of the filter is partially driven by gravity [0029], and that the vacuum enhances this. As such, maintaining a geodetic difference in height between the filter and the collection volume would have been obvious to one of ordinary skill in the art, to ensure that gravity acts to enhance fluid flow rather than resist it. Regarding the specific height difference employed, Dieter teaches that thresholds for pressure and the like must be established based on operating conditions [0030]. See MPEP 2144.05 II.A; "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). Optimization of the height difference (and thus overall driving forces) would have been obvious to one of ordinary skill in the art in view of these considerations. With respect to claims 4 and 14, Van Schie teaches that the underpressure is at least partially driven by fluid being withdrawn from the collection volume [pg. 11 lines 8-21]; when applied to the combined system, this would further include fluid moving through the outlet line. With respect to claims 5, 6, 15, and 16, both Van Schie and Dieter teach controlling the differential pressure to desired values, which would necessarily also control the passing time (as higher pressure causes faster filtration). They are silent to the specific claimed ranges. Dieter teaches, for example, that the negative pressure threshold must be established based on operating conditions [0030]. See MPEP 2144.05 II.A; "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). Optimization of the pressure differential (and thus passing time) would have been obvious to one of ordinary skill in the art in view of these considerations. With respect to claims 7 and 17, the instant specification suggests that the claimed property is an inherent result of using a filter cloth structure; Dieter teaches a fabric vacuum belt filter [0024], as does Van Schie [pg. 6 lines 11-20]. As such, they are interpreted as possessing such properties absent clarification of the structural requirements. With respect to claims 8 and 18, see MPEP 2144.04 IV.B; changes in shape are obvious to those of ordinary skill in the art, such that selection of a tank configuration which has a larger horizontal extension compared to its vertical extension represents an obvious change of shape for one of ordinary skill in the art. Further, as above, Dieter teaches that it may be useful for certain elements to be provided in a low profile configuration, and it would have been obvious to apply this same principle to the collection tank. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to BRADLEY R SPIES whose telephone number is (571)272-3469. The examiner can normally be reached Mon-Thurs 8AM-4PM. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jennifer Dieterle can be reached at (571)270-7872. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /BRADLEY R SPIES/Primary Examiner, Art Unit 1777
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Prosecution Timeline

Dec 22, 2023
Application Filed
Mar 10, 2026
Non-Final Rejection — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
74%
Grant Probability
95%
With Interview (+20.9%)
2y 6m
Median Time to Grant
Low
PTA Risk
Based on 807 resolved cases by this examiner. Grant probability derived from career allow rate.

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